+ * The puzzle rules are:
* 1. Only one disc can be moved at a time.
* 2. A disc can only be placed on top of a larger disc.
* 3. All discs must start on one pole and end on another.
+ *
*
- * This implementation recursively calculates the steps required to solve the puzzle and stores them
- * in a provided list.
+ *
+ * The recursion follows three steps:
+ * 1. Move {@code n-1} discs from start to intermediate.
+ * 2. Move the largest disc from start to end.
+ * 3. Move {@code n-1} discs from intermediate to end.
+ *
*
*
* This method is called recursively to move n-1 discs
@@ -51,15 +57,20 @@ private TowerOfHanoi() {
*
*/
public static void shift(int n, String startPole, String intermediatePole, String endPole, List result) {
- if (n != 0) {
- // Move n-1 discs from startPole to intermediatePole
- shift(n - 1, startPole, endPole, intermediatePole, result);
+ if (n < 0) {
+ throw new IllegalArgumentException("Number of discs must be non-negative");
+ }
+ if (n == 0) {
+ return;
+ }
- // Add the move of the nth disc from startPole to endPole
- result.add(String.format("Move %d from %s to %s", n, startPole, endPole));
+ // Move n-1 discs from startPole to intermediatePole
+ shift(n - 1, startPole, endPole, intermediatePole, result);
- // Move the n-1 discs from intermediatePole to endPole
- shift(n - 1, intermediatePole, startPole, endPole, result);
- }
+ // Add the move of the nth disc from startPole to endPole
+ result.add(String.format("Move %d from %s to %s", n, startPole, endPole));
+
+ // Move the n-1 discs from intermediatePole to endPole
+ shift(n - 1, intermediatePole, startPole, endPole, result);
}
}
diff --git a/src/main/java/com/thealgorithms/recursion/FibonacciSeries.java b/src/main/java/com/thealgorithms/recursion/FibonacciSeries.java
index 9bc6da2f7443..9c809858099e 100644
--- a/src/main/java/com/thealgorithms/recursion/FibonacciSeries.java
+++ b/src/main/java/com/thealgorithms/recursion/FibonacciSeries.java
@@ -1,16 +1,26 @@
package com.thealgorithms.recursion;
-/*
- The Fibonacci series is a sequence of numbers where each number is the sum of the two preceding ones,
- starting with 0 and 1.
- NUMBER 0 1 2 3 4 5 6 7 8 9 10 ...
- FIBONACCI 0 1 1 2 3 5 8 13 21 34 55 ...
-*/
+/**
+ * The Fibonacci series is a sequence of numbers where each number is the sum of the two preceding ones,
+ * starting with 0 and 1.
+ *
+ * Example:
+ * 0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55 ...
+ *
+ */
public final class FibonacciSeries {
private FibonacciSeries() {
throw new UnsupportedOperationException("Utility class");
}
+
+ /**
+ * Calculates the nth term in the Fibonacci sequence using recursion.
+ *
+ * @param n the position in the Fibonacci sequence (must be non-negative)
+ * @return the nth Fibonacci number
+ * @throws IllegalArgumentException if n is negative
+ */
public static int fibonacci(int n) {
if (n < 0) {
throw new IllegalArgumentException("n must be a non-negative integer");
diff --git a/src/main/java/com/thealgorithms/searches/BinarySearch.java b/src/main/java/com/thealgorithms/searches/BinarySearch.java
index bedad1667f33..7a5361b280ea 100644
--- a/src/main/java/com/thealgorithms/searches/BinarySearch.java
+++ b/src/main/java/com/thealgorithms/searches/BinarySearch.java
@@ -3,12 +3,32 @@
import com.thealgorithms.devutils.searches.SearchAlgorithm;
/**
- * Binary search is one of the most popular algorithms The algorithm finds the
- * position of a target value within a sorted array
+ * Binary Search Algorithm Implementation
*
- *
- * Worst-case performance O(log n) Best-case performance O(1) Average
- * performance O(log n) Worst-case space complexity O(1)
+ *
Binary search is one of the most efficient searching algorithms for finding a target element
+ * in a SORTED array. It works by repeatedly dividing the search space in half, eliminating half of
+ * the remaining elements in each step.
+ *
+ *
IMPORTANT: This algorithm ONLY works correctly if the input array is sorted in ascending
+ * order.
+ *
+ *
Algorithm Overview: 1. Start with the entire array (left = 0, right = array.length - 1) 2.
+ * Calculate the middle index 3. Compare the middle element with the target: - If middle element
+ * equals target: Found! Return the index - If middle element is less than target: Search the right
+ * half - If middle element is greater than target: Search the left half 4. Repeat until element is
+ * found or search space is exhausted
+ *
+ *
Performance Analysis: - Best-case time complexity: O(1) - Element found at middle on first
+ * try - Average-case time complexity: O(log n) - Most common scenario - Worst-case time
+ * complexity: O(log n) - Element not found or at extreme end - Space complexity: O(1) - Only uses
+ * a constant amount of extra space
+ *
+ *
Example Walkthrough: Array: [1, 3, 5, 7, 9, 11, 13, 15, 17, 19] Target: 7
+ *
+ *
Step 1: left=0, right=9, mid=4, array[4]=9 (9 > 7, search left half) Step 2: left=0,
+ * right=3, mid=1, array[1]=3 (3 < 7, search right half) Step 3: left=2, right=3, mid=2,
+ * array[2]=5 (5 < 7, search right half) Step 4: left=3, right=3, mid=3, array[3]=7 (Found!
+ * Return index 3)
*
* @author Varun Upadhyay (https://github.com/varunu28)
* @author Podshivalov Nikita (https://github.com/nikitap492)
@@ -18,38 +38,89 @@
class BinarySearch implements SearchAlgorithm {
/**
- * @param array is an array where the element should be found
- * @param key is an element which should be found
- * @param is any comparable type
- * @return index of the element
+ * Generic method to perform binary search on any comparable type. This is the main entry point
+ * for binary search operations.
+ *
+ * Example Usage:
+ *
+ * Integer[] numbers = {1, 3, 5, 7, 9, 11};
+ * int result = new BinarySearch().find(numbers, 7);
+ * // result will be 3 (index of element 7)
+ *
+ * int notFound = new BinarySearch().find(numbers, 4);
+ * // notFound will be -1 (element 4 does not exist)
+ *
+ *
+ * @param The type of elements in the array (must be Comparable)
+ * @param array The sorted array to search in (MUST be sorted in ascending order)
+ * @param key The element to search for
+ * @return The index of the key if found, -1 if not found or if array is null/empty
*/
@Override
public > int find(T[] array, T key) {
+ // Handle edge case: empty array
+ if (array == null || array.length == 0) {
+ return -1;
+ }
+
+ // Delegate to the core search implementation
return search(array, key, 0, array.length - 1);
}
/**
- * This method implements the Generic Binary Search
+ * Core recursive implementation of binary search algorithm. This method divides the problem
+ * into smaller subproblems recursively.
+ *
+ * How it works:
+ *
+ * - Calculate the middle index to avoid integer overflow
+ * - Check if middle element matches the target
+ * - If not, recursively search either left or right half
+ * - Base case: left > right means element not found
+ *
+ *
+ * Time Complexity: O(log n) because we halve the search space each time.
+ * Space Complexity: O(log n) due to recursive call stack.
*
- * @param array The array to make the binary search
- * @param key The number you are looking for
- * @param left The lower bound
- * @param right The upper bound
- * @return the location of the key
+ * @param The type of elements (must be Comparable)
+ * @param array The sorted array to search in
+ * @param key The element we're looking for
+ * @param left The leftmost index of current search range (inclusive)
+ * @param right The rightmost index of current search range (inclusive)
+ * @return The index where key is located, or -1 if not found
*/
private > int search(T[] array, T key, int left, int right) {
+ // Base case: Search space is exhausted
+ // This happens when left pointer crosses right pointer
if (right < left) {
- return -1; // this means that the key not found
+ return -1; // Key not found in the array
}
- // find median
- int median = (left + right) >>> 1;
+
+ // Calculate middle index
+ // Using (left + right) / 2 could cause integer overflow for large arrays
+ // So we use: left + (right - left) / 2 which is mathematically equivalent
+ // but prevents overflow
+ int median = (left + right) >>> 1; // Unsigned right shift is faster division by 2
+
+ // Get the value at middle position for comparison
int comp = key.compareTo(array[median]);
+ // Case 1: Found the target element at middle position
if (comp == 0) {
- return median;
- } else if (comp < 0) {
+ return median; // Return the index where element was found
+ }
+ // Case 2: Target is smaller than middle element
+ // This means if target exists, it must be in the LEFT half
+ else if (comp < 0) {
+ // Recursively search the left half
+ // New search range: [left, median - 1]
return search(array, key, left, median - 1);
- } else {
+ }
+ // Case 3: Target is greater than middle element
+ // This means if target exists, it must be in the RIGHT half
+ else {
+ // Recursively search the right half
+ // New search range: [median + 1, right]
return search(array, key, median + 1, right);
}
}
diff --git a/src/main/java/com/thealgorithms/searches/LinearSearch.java b/src/main/java/com/thealgorithms/searches/LinearSearch.java
index c7b70edb5112..cb483d8dfedc 100644
--- a/src/main/java/com/thealgorithms/searches/LinearSearch.java
+++ b/src/main/java/com/thealgorithms/searches/LinearSearch.java
@@ -1,21 +1,26 @@
package com.thealgorithms.searches;
import com.thealgorithms.devutils.searches.SearchAlgorithm;
-
/**
- * Linear search is the easiest search algorithm It works with sorted and
- * unsorted arrays (an binary search works only with sorted array) This
- * algorithm just compares all elements of an array to find a value
+ * Linear Search is a simple searching algorithm that checks
+ * each element of the array sequentially until the target
+ * value is found or the array ends.
+ *
+ * It works for both sorted and unsorted arrays.
*
- *
- * Worst-case performance O(n) Best-case performance O(1) Average performance
- * O(n) Worst-case space complexity
+ * Time Complexity:
+ * - Best case: O(1)
+ * - Average case: O(n)
+ * - Worst case: O(n)
*
- * @author Varun Upadhyay (https://github.com/varunu28)
- * @author Podshivalov Nikita (https://github.com/nikitap492)
+ * Space Complexity: O(1)
+ *
+ * @author Varun Upadhyay
+ * @author Podshivalov Nikita
* @see BinarySearch
* @see SearchAlgorithm
*/
+
public class LinearSearch implements SearchAlgorithm {
/**
diff --git a/src/main/java/com/thealgorithms/searches/PerfectBinarySearch.java b/src/main/java/com/thealgorithms/searches/PerfectBinarySearch.java
deleted file mode 100644
index 495e2e41bc5b..000000000000
--- a/src/main/java/com/thealgorithms/searches/PerfectBinarySearch.java
+++ /dev/null
@@ -1,54 +0,0 @@
-package com.thealgorithms.searches;
-
-import com.thealgorithms.devutils.searches.SearchAlgorithm;
-
-/**
- * Binary search is one of the most popular algorithms The algorithm finds the
- * position of a target value within a sorted array
- *
- *
- * Worst-case performance O(log n) Best-case performance O(1) Average
- * performance O(log n) Worst-case space complexity O(1)
- *
- * @author D Sunil (https://github.com/sunilnitdgp)
- * @see SearchAlgorithm
- */
-
-public class PerfectBinarySearch implements SearchAlgorithm {
-
- /**
- * @param array is an array where the element should be found
- * @param key is an element which should be found
- * @param is any comparable type
- * @return index of the element
- */
- @Override
- public > int find(T[] array, T key) {
- return search(array, key, 0, array.length - 1);
- }
-
- /**
- * This method implements the Generic Binary Search iteratively.
- *
- * @param array The array to make the binary search
- * @param key The number you are looking for
- * @return the location of the key, or -1 if not found
- */
- private static > int search(T[] array, T key, int left, int right) {
- while (left <= right) {
- int median = (left + right) >>> 1;
- int comp = key.compareTo(array[median]);
-
- if (comp == 0) {
- return median; // Key found
- }
-
- if (comp < 0) {
- right = median - 1; // Adjust the right bound
- } else {
- left = median + 1; // Adjust the left bound
- }
- }
- return -1; // Key not found
- }
-}
diff --git a/src/main/java/com/thealgorithms/searches/RecursiveBinarySearch.java b/src/main/java/com/thealgorithms/searches/RecursiveBinarySearch.java
index daf0c12c0978..1716e78964ae 100644
--- a/src/main/java/com/thealgorithms/searches/RecursiveBinarySearch.java
+++ b/src/main/java/com/thealgorithms/searches/RecursiveBinarySearch.java
@@ -23,28 +23,27 @@ public int find(T[] arr, T target) {
// Recursive binary search function
public int binsear(T[] arr, int left, int right, T target) {
- if (right >= left) {
- int mid = left + (right - left) / 2;
-
- // Compare the element at the middle with the target
- int comparison = arr[mid].compareTo(target);
+ if (right < left) {
+ // Element is not present in the array
+ return -1;
+ }
+ final int mid = left + (right - left) / 2;
- // If the element is equal to the target, return its index
- if (comparison == 0) {
- return mid;
- }
+ // Compare the element at the middle with the target
+ final int comparison = arr[mid].compareTo(target);
- // If the element is greater than the target, search in the left subarray
- if (comparison > 0) {
- return binsear(arr, left, mid - 1, target);
- }
+ // If the element is equal to the target, return its index
+ if (comparison == 0) {
+ return mid;
+ }
- // Otherwise, search in the right subarray
- return binsear(arr, mid + 1, right, target);
+ // If the element is greater than the target, search in the left subarray
+ if (comparison > 0) {
+ return binsear(arr, left, mid - 1, target);
}
- // Element is not present in the array
- return -1;
+ // Otherwise, search in the right subarray
+ return binsear(arr, mid + 1, right, target);
}
public static void main(String[] args) {
diff --git a/src/main/java/com/thealgorithms/searches/SortOrderAgnosticBinarySearch.java b/src/main/java/com/thealgorithms/searches/SortOrderAgnosticBinarySearch.java
deleted file mode 100644
index 6a2a46c2821f..000000000000
--- a/src/main/java/com/thealgorithms/searches/SortOrderAgnosticBinarySearch.java
+++ /dev/null
@@ -1,30 +0,0 @@
-package com.thealgorithms.searches;
-public final class SortOrderAgnosticBinarySearch {
- private SortOrderAgnosticBinarySearch() {
- }
- public static int find(int[] arr, int key) {
- int start = 0;
- int end = arr.length - 1;
- boolean arrDescending = arr[start] > arr[end]; // checking for Array is in ascending order or descending order.
- while (start <= end) {
- int mid = end - start / 2;
- if (arr[mid] == key) {
- return mid;
- }
- if (arrDescending) { // boolean is true then our array is in descending order
- if (key < arr[mid]) {
- start = mid + 1;
- } else {
- end = mid - 1;
- }
- } else { // otherwise our array is in ascending order
- if (key > arr[mid]) {
- start = mid + 1;
- } else {
- end = mid - 1;
- }
- }
- }
- return -1;
- }
-}
diff --git a/src/main/java/com/thealgorithms/sorts/InsertionSort.java b/src/main/java/com/thealgorithms/sorts/InsertionSort.java
index fdbfd9cd1cfa..1e42f2a61271 100644
--- a/src/main/java/com/thealgorithms/sorts/InsertionSort.java
+++ b/src/main/java/com/thealgorithms/sorts/InsertionSort.java
@@ -33,30 +33,30 @@ public > T[] sort(T[] array) {
}
/**
- * Sorts a subarray of the given array using the standard Insertion Sort algorithm.
+ * Sorts a subarray of the given items using the standard Insertion Sort algorithm.
*
- * @param array The array to be sorted
- * @param lo The starting index of the subarray
- * @param hi The ending index of the subarray (exclusive)
- * @param The type of elements in the array, which must be comparable
- * @return The sorted array
+ * @param items The items to be sorted
+ * @param startIndex The starting index of the subarray
+ * @param endIndex The ending index of the subarray (exclusive)
+ * @param The type of elements in the items, which must be comparable
+ * @return The sorted items
*/
- public > T[] sort(T[] array, final int lo, final int hi) {
- if (array == null || lo >= hi) {
- return array;
+ public > T[] sort(T[] items, final int startIndex, final int endIndex) {
+ if (items == null || startIndex >= endIndex) {
+ return items;
}
- for (int i = lo + 1; i < hi; i++) {
- final T key = array[i];
+ for (int i = startIndex + 1; i < endIndex; i++) {
+ final T key = items[i];
int j = i - 1;
- while (j >= lo && SortUtils.less(key, array[j])) {
- array[j + 1] = array[j];
+ while (j >= startIndex && SortUtils.less(key, items[j])) {
+ items[j + 1] = items[j];
j--;
}
- array[j + 1] = key;
+ items[j + 1] = key;
}
- return array;
+ return items;
}
/**
diff --git a/src/main/java/com/thealgorithms/sorts/MergeSort.java b/src/main/java/com/thealgorithms/sorts/MergeSort.java
index f7a7c8da004d..5db9c48b4f61 100644
--- a/src/main/java/com/thealgorithms/sorts/MergeSort.java
+++ b/src/main/java/com/thealgorithms/sorts/MergeSort.java
@@ -10,7 +10,7 @@
@SuppressWarnings("rawtypes")
class MergeSort implements SortAlgorithm {
- private Comparable[] aux;
+ private Comparable[] tempArray;
/**
* Generic merge sort algorithm.
@@ -26,7 +26,7 @@ class MergeSort implements SortAlgorithm {
*/
@Override
public > T[] sort(T[] unsorted) {
- aux = new Comparable[unsorted.length];
+ tempArray = new Comparable[unsorted.length];
doSort(unsorted, 0, unsorted.length - 1);
return unsorted;
}
@@ -58,17 +58,17 @@ private > void doSort(T[] arr, int left, int right) {
private > void merge(T[] arr, int left, int mid, int right) {
int i = left;
int j = mid + 1;
- System.arraycopy(arr, left, aux, left, right + 1 - left);
+ System.arraycopy(arr, left, tempArray, left, right + 1 - left);
for (int k = left; k <= right; k++) {
if (j > right) {
- arr[k] = (T) aux[i++];
+ arr[k] = (T) tempArray[i++];
} else if (i > mid) {
- arr[k] = (T) aux[j++];
- } else if (less(aux[j], aux[i])) {
- arr[k] = (T) aux[j++];
+ arr[k] = (T) tempArray[j++];
+ } else if (less(tempArray[j], tempArray[i])) {
+ arr[k] = (T) tempArray[j++];
} else {
- arr[k] = (T) aux[i++];
+ arr[k] = (T) tempArray[i++];
}
}
}
diff --git a/src/main/java/com/thealgorithms/sorts/PancakeSort.java b/src/main/java/com/thealgorithms/sorts/PancakeSort.java
index 6079672a1d77..6522aefd7ae3 100644
--- a/src/main/java/com/thealgorithms/sorts/PancakeSort.java
+++ b/src/main/java/com/thealgorithms/sorts/PancakeSort.java
@@ -15,7 +15,7 @@ public > T[] sort(T[] array) {
}
for (int currentSize = 0; currentSize < array.length; currentSize++) {
- int maxIndex = findMaxIndex(array, currentSize);
+ int maxIndex = findIndexOfMax(array, currentSize);
SortUtils.flip(array, maxIndex, array.length - 1 - currentSize);
}
@@ -30,7 +30,7 @@ public > T[] sort(T[] array) {
* @param the type of elements in the array
* @return the index of the maximum element
*/
- private > int findMaxIndex(T[] array, int currentSize) {
+ private > int findIndexOfMax(T[] array, int currentSize) {
T max = array[0];
int maxIndex = 0;
for (int i = 0; i < array.length - currentSize; i++) {
diff --git a/src/main/java/com/thealgorithms/strings/KMP.java b/src/main/java/com/thealgorithms/strings/KMP.java
index 07d3b0415006..0317abe6f39a 100644
--- a/src/main/java/com/thealgorithms/strings/KMP.java
+++ b/src/main/java/com/thealgorithms/strings/KMP.java
@@ -1,5 +1,8 @@
package com.thealgorithms.strings;
+import java.util.ArrayList;
+import java.util.List;
+
/**
* Implementation of KnuthβMorrisβPratt algorithm Usage: see the main function
* for an example
@@ -8,16 +11,19 @@ public final class KMP {
private KMP() {
}
- // a working example
-
- public static void main(String[] args) {
- final String haystack = "AAAAABAAABA"; // This is the full string
- final String needle = "AAAA"; // This is the substring that we want to find
- kmpMatcher(haystack, needle);
- }
+ /**
+ * find the starting index in string haystack[] that matches the search word P[]
+ *
+ * @param haystack The text to be searched
+ * @param needle The pattern to be searched for
+ * @return A list of starting indices where the pattern is found
+ */
+ public static List kmpMatcher(final String haystack, final String needle) {
+ List occurrences = new ArrayList<>();
+ if (haystack == null || needle == null || needle.isEmpty()) {
+ return occurrences;
+ }
- // find the starting index in string haystack[] that matches the search word P[]
- public static void kmpMatcher(final String haystack, final String needle) {
final int m = haystack.length();
final int n = needle.length();
final int[] pi = computePrefixFunction(needle);
@@ -32,10 +38,11 @@ public static void kmpMatcher(final String haystack, final String needle) {
}
if (q == n) {
- System.out.println("Pattern starts: " + (i + 1 - n));
+ occurrences.add(i + 1 - n);
q = pi[q - 1];
}
}
+ return occurrences;
}
// return the prefix function
diff --git a/src/main/java/com/thealgorithms/strings/KasaiAlgorithm.java b/src/main/java/com/thealgorithms/strings/KasaiAlgorithm.java
new file mode 100644
index 000000000000..b8b10dcf4538
--- /dev/null
+++ b/src/main/java/com/thealgorithms/strings/KasaiAlgorithm.java
@@ -0,0 +1,79 @@
+package com.thealgorithms.strings;
+
+/**
+ * Kasai's Algorithm for constructing the Longest Common Prefix (LCP) array.
+ *
+ *
+ * The LCP array stores the lengths of the longest common prefixes between
+ * lexicographically adjacent suffixes of a string. Kasai's algorithm computes
+ * this array in O(N) time given the string and its suffix array.
+ *
+ *
+ * @see LCP array - Wikipedia
+ */
+public final class KasaiAlgorithm {
+
+ private KasaiAlgorithm() {
+ }
+
+ /**
+ * Computes the LCP array using Kasai's algorithm.
+ *
+ * @param text the original string
+ * @param suffixArr the suffix array of the string
+ * @return the LCP array of length N, where LCP[i] is the length of the longest
+ * common prefix of the suffixes indexed by suffixArr[i] and suffixArr[i+1].
+ * The last element LCP[N-1] is always 0.
+ * @throws IllegalArgumentException if text or suffixArr is null, or their lengths differ
+ */
+ public static int[] kasai(String text, int[] suffixArr) {
+ if (text == null || suffixArr == null) {
+ throw new IllegalArgumentException("Text and suffix array must not be null.");
+ }
+ int n = text.length();
+ if (suffixArr.length != n) {
+ throw new IllegalArgumentException("Suffix array length must match text length.");
+ }
+ if (n == 0) {
+ return new int[0];
+ }
+
+ // Compute the inverse suffix array
+ // invSuff[i] stores the index of the suffix text.substring(i) in the suffix array
+ int[] invSuff = new int[n];
+ for (int i = 0; i < n; i++) {
+ if (suffixArr[i] < 0 || suffixArr[i] >= n) {
+ throw new IllegalArgumentException("Suffix array contains out-of-bounds index.");
+ }
+ invSuff[suffixArr[i]] = i;
+ }
+
+ int[] lcp = new int[n];
+ int k = 0; // Length of the longest common prefix
+
+ for (int i = 0; i < n; i++) {
+ // Suffix at index i has not a next suffix in suffix array
+ int rank = invSuff[i];
+ if (rank == n - 1) {
+ k = 0;
+ continue;
+ }
+
+ int nextSuffixIndex = suffixArr[rank + 1];
+
+ // Directly match characters to find LCP
+ while (i + k < n && nextSuffixIndex + k < n && text.charAt(i + k) == text.charAt(nextSuffixIndex + k)) {
+ k++;
+ }
+
+ lcp[rank] = k;
+
+ // Delete the starting character from the string
+ if (k > 0) {
+ k--;
+ }
+ }
+
+ return lcp;
+ }
+}
diff --git a/src/main/java/com/thealgorithms/strings/LongestNonRepetitiveSubstring.java b/src/main/java/com/thealgorithms/strings/LongestNonRepetitiveSubstring.java
index 6808cd50602f..51e8dc6b02c3 100644
--- a/src/main/java/com/thealgorithms/strings/LongestNonRepetitiveSubstring.java
+++ b/src/main/java/com/thealgorithms/strings/LongestNonRepetitiveSubstring.java
@@ -13,6 +13,12 @@ private LongestNonRepetitiveSubstring() {
/**
* Finds the length of the longest substring without repeating characters.
*
+ * Uses the sliding window technique with a HashMap to track
+ * the last seen index of each character.
+ *
+ * Time Complexity: O(n), where n is the length of the input string.
+ * Space Complexity: O(min(n, m)), where m is the size of the character set.
+ *
* @param s the input string
* @return the length of the longest non-repetitive substring
*/
diff --git a/src/main/java/com/thealgorithms/strings/LongestPalindromicSubstring.java b/src/main/java/com/thealgorithms/strings/LongestPalindromicSubstring.java
deleted file mode 100644
index ca500357ba77..000000000000
--- a/src/main/java/com/thealgorithms/strings/LongestPalindromicSubstring.java
+++ /dev/null
@@ -1,37 +0,0 @@
-package com.thealgorithms.strings;
-
-final class LongestPalindromicSubstring {
- private LongestPalindromicSubstring() {
- }
-
- /**
- * Finds the longest palindromic substring in the given string.
- *
- * @param s the input string
- * @return the longest palindromic substring
- */
- public static String longestPalindrome(String s) {
- if (s == null || s.isEmpty()) {
- return "";
- }
- String maxStr = "";
- for (int i = 0; i < s.length(); ++i) {
- for (int j = i; j < s.length(); ++j) {
- if (isValid(s, i, j) && (j - i + 1 > maxStr.length())) {
- maxStr = s.substring(i, j + 1);
- }
- }
- }
- return maxStr;
- }
-
- private static boolean isValid(String s, int lo, int hi) {
- int n = hi - lo + 1;
- for (int i = 0; i < n / 2; ++i) {
- if (s.charAt(lo + i) != s.charAt(hi - i)) {
- return false;
- }
- }
- return true;
- }
-}
diff --git a/src/main/java/com/thealgorithms/strings/LongestRepeatedSubstring.java b/src/main/java/com/thealgorithms/strings/LongestRepeatedSubstring.java
new file mode 100644
index 000000000000..87c9278fd4bf
--- /dev/null
+++ b/src/main/java/com/thealgorithms/strings/LongestRepeatedSubstring.java
@@ -0,0 +1,83 @@
+package com.thealgorithms.strings;
+
+/**
+ * Finds the longest substring that occurs at least twice in a given string.
+ *
+ * Uses the suffix array (via {@link SuffixArray}) and Kasai's algorithm
+ * to build the LCP (Longest Common Prefix) array, then returns the substring
+ * corresponding to the maximum LCP value.
+ *
+ * Time complexity: O(n logΒ² n) for suffix array construction + O(n) for LCP.
+ *
+ * @see Longest repeated substring problem
+ * @see SuffixArray
+ */
+public final class LongestRepeatedSubstring {
+
+ private LongestRepeatedSubstring() {
+ }
+
+ /**
+ * Returns the longest substring that appears at least twice in the given text.
+ *
+ * @param text the input string
+ * @return the longest repeated substring, or an empty string if none exists
+ */
+ public static String longestRepeatedSubstring(String text) {
+ if (text == null || text.length() <= 1) {
+ return "";
+ }
+
+ final int[] suffixArray = SuffixArray.buildSuffixArray(text);
+ final int[] lcp = buildLcpArray(text, suffixArray);
+
+ int maxLen = 0;
+ int maxIdx = 0;
+ for (int i = 0; i < lcp.length; i++) {
+ if (lcp[i] > maxLen) {
+ maxLen = lcp[i];
+ maxIdx = suffixArray[i + 1];
+ }
+ }
+
+ return text.substring(maxIdx, maxIdx + maxLen);
+ }
+
+ /**
+ * Builds the LCP (Longest Common Prefix) array using Kasai's algorithm.
+ *
+ * LCP[i] is the length of the longest common prefix between the suffixes
+ * at positions suffixArray[i] and suffixArray[i+1] in sorted order.
+ *
+ * @param text the original string
+ * @param suffixArray the suffix array of the string
+ * @return the LCP array of length n-1
+ */
+ static int[] buildLcpArray(String text, int[] suffixArray) {
+ final int n = text.length();
+ final int[] rank = new int[n];
+ final int[] lcp = new int[n - 1];
+
+ for (int i = 0; i < n; i++) {
+ rank[suffixArray[i]] = i;
+ }
+
+ int k = 0;
+ for (int i = 0; i < n; i++) {
+ if (rank[i] == n - 1) {
+ k = 0;
+ continue;
+ }
+ final int j = suffixArray[rank[i] + 1];
+ while (i + k < n && j + k < n && text.charAt(i + k) == text.charAt(j + k)) {
+ k++;
+ }
+ lcp[rank[i]] = k;
+ if (k > 0) {
+ k--;
+ }
+ }
+
+ return lcp;
+ }
+}
diff --git a/src/main/java/com/thealgorithms/strings/MyAtoi.java b/src/main/java/com/thealgorithms/strings/MyAtoi.java
index 5a7c2ce53b1c..92de4039a582 100644
--- a/src/main/java/com/thealgorithms/strings/MyAtoi.java
+++ b/src/main/java/com/thealgorithms/strings/MyAtoi.java
@@ -45,7 +45,9 @@ public static int myAtoi(String s) {
int number = 0;
while (index < length) {
char ch = s.charAt(index);
- if (!Character.isDigit(ch)) {
+
+ // Accept only ASCII digits
+ if (ch < '0' || ch > '9') {
break;
}
diff --git a/src/main/java/com/thealgorithms/strings/RabinKarp.java b/src/main/java/com/thealgorithms/strings/RabinKarp.java
index bb8df3358453..be17f87c3656 100644
--- a/src/main/java/com/thealgorithms/strings/RabinKarp.java
+++ b/src/main/java/com/thealgorithms/strings/RabinKarp.java
@@ -1,32 +1,30 @@
package com.thealgorithms.strings;
-import java.util.Scanner;
+import java.util.ArrayList;
+import java.util.List;
/**
* @author Prateek Kumar Oraon (https://github.com/prateekKrOraon)
*
- An implementation of Rabin-Karp string matching algorithm
- Program will simply end if there is no match
+ * An implementation of Rabin-Karp string matching algorithm
+ * Program will simply end if there is no match
*/
public final class RabinKarp {
private RabinKarp() {
}
- public static Scanner scanner = null;
- public static final int ALPHABET_SIZE = 256;
+ private static final int ALPHABET_SIZE = 256;
- public static void main(String[] args) {
- scanner = new Scanner(System.in);
- System.out.println("Enter String");
- String text = scanner.nextLine();
- System.out.println("Enter pattern");
- String pattern = scanner.nextLine();
-
- int q = 101;
- searchPat(text, pattern, q);
+ public static List search(String text, String pattern) {
+ return search(text, pattern, 101);
}
- private static void searchPat(String text, String pattern, int q) {
+ public static List search(String text, String pattern, int q) {
+ List occurrences = new ArrayList<>();
+ if (text == null || pattern == null || pattern.isEmpty()) {
+ return occurrences;
+ }
+
int m = pattern.length();
int n = text.length();
int t = 0;
@@ -35,48 +33,42 @@ private static void searchPat(String text, String pattern, int q) {
int j = 0;
int i = 0;
- h = (int) Math.pow(ALPHABET_SIZE, m - 1) % q;
+ if (m > n) {
+ return new ArrayList<>();
+ }
+
+ // h = pow(ALPHABET_SIZE, m-1) % q
+ for (i = 0; i < m - 1; i++) {
+ h = h * ALPHABET_SIZE % q;
+ }
for (i = 0; i < m; i++) {
- // hash value is calculated for each character and then added with the hash value of the
- // next character for pattern as well as the text for length equal to the length of
- // pattern
p = (ALPHABET_SIZE * p + pattern.charAt(i)) % q;
t = (ALPHABET_SIZE * t + text.charAt(i)) % q;
}
for (i = 0; i <= n - m; i++) {
- // if the calculated hash value of the pattern and text matches then
- // all the characters of the pattern is matched with the text of length equal to length
- // of the pattern if all matches then pattern exist in string if not then the hash value
- // of the first character of the text is subtracted and hash value of the next character
- // after the end of the evaluated characters is added
if (p == t) {
- // if hash value matches then the individual characters are matched
for (j = 0; j < m; j++) {
- // if not matched then break out of the loop
if (text.charAt(i + j) != pattern.charAt(j)) {
break;
}
}
- // if all characters are matched then pattern exist in the string
if (j == m) {
- System.out.println("Pattern found at index " + i);
+ occurrences.add(i);
}
}
- // if i 0) {
+ result.deleteCharAt(result.length() - 1);
+ }
+ } else {
+ result.append(c);
+ }
+ }
+ return result.toString();
+ }
+}
diff --git a/src/main/java/com/thealgorithms/strings/TopKFrequentWords.java b/src/main/java/com/thealgorithms/strings/TopKFrequentWords.java
new file mode 100644
index 000000000000..106de304cf40
--- /dev/null
+++ b/src/main/java/com/thealgorithms/strings/TopKFrequentWords.java
@@ -0,0 +1,56 @@
+package com.thealgorithms.strings;
+
+import java.util.ArrayList;
+import java.util.Comparator;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+/**
+ * Utility class to find the top-k most frequent words.
+ *
+ * Words are ranked by frequency in descending order. For equal frequencies,
+ * words are ranked in lexicographical ascending order.
+ *
+ *
Reference:
+ * https://en.wikipedia.org/wiki/Top-k_problem
+ *
+ */
+public final class TopKFrequentWords {
+ private TopKFrequentWords() {
+ }
+
+ /**
+ * Finds the k most frequent words.
+ *
+ * @param words input array of words
+ * @param k number of words to return
+ * @return list of top-k words ordered by frequency then lexicographical order
+ * @throws IllegalArgumentException if words is null, k is negative, or words contains null
+ */
+ public static List findTopKFrequentWords(String[] words, int k) {
+ if (words == null) {
+ throw new IllegalArgumentException("Input words array cannot be null.");
+ }
+ if (k < 0) {
+ throw new IllegalArgumentException("k cannot be negative.");
+ }
+ if (k == 0 || words.length == 0) {
+ return List.of();
+ }
+
+ Map frequency = new HashMap<>();
+ for (String word : words) {
+ if (word == null) {
+ throw new IllegalArgumentException("Input words cannot contain null values.");
+ }
+ frequency.put(word, frequency.getOrDefault(word, 0) + 1);
+ }
+
+ List candidates = new ArrayList<>(frequency.keySet());
+ candidates.sort(Comparator.comparingInt(frequency::get).reversed().thenComparing(Comparator.naturalOrder()));
+
+ int limit = Math.min(k, candidates.size());
+ return new ArrayList<>(candidates.subList(0, limit));
+ }
+}
diff --git a/src/main/java/com/thealgorithms/strings/ValidParentheses.java b/src/main/java/com/thealgorithms/strings/ValidParentheses.java
deleted file mode 100644
index 25a72f379dec..000000000000
--- a/src/main/java/com/thealgorithms/strings/ValidParentheses.java
+++ /dev/null
@@ -1,53 +0,0 @@
-package com.thealgorithms.strings;
-
-import java.util.ArrayDeque;
-import java.util.Deque;
-import java.util.Map;
-
-/**
- * Validates if a given string has valid matching parentheses.
- *
- * A string is considered valid if:
- *
- * - Open brackets are closed by the same type of brackets.
- * - Brackets are closed in the correct order.
- * - Every closing bracket has a corresponding open bracket of the same type.
- *
- *
- * Allowed characters: '(', ')', '{', '}', '[', ']'
- */
-public final class ValidParentheses {
- private ValidParentheses() {
- }
-
- private static final Map BRACKET_PAIRS = Map.of(')', '(', '}', '{', ']', '[');
-
- /**
- * Checks if the input string has valid parentheses.
- *
- * @param s the string containing only bracket characters
- * @return true if valid, false otherwise
- * @throws IllegalArgumentException if the string contains invalid characters or is null
- */
- public static boolean isValid(String s) {
- if (s == null) {
- throw new IllegalArgumentException("Input string cannot be null");
- }
-
- Deque stack = new ArrayDeque<>();
-
- for (char c : s.toCharArray()) {
- if (BRACKET_PAIRS.containsValue(c)) {
- stack.push(c); // opening bracket
- } else if (BRACKET_PAIRS.containsKey(c)) {
- if (stack.isEmpty() || stack.pop() != BRACKET_PAIRS.get(c)) {
- return false;
- }
- } else {
- throw new IllegalArgumentException("Unexpected character: " + c);
- }
- }
-
- return stack.isEmpty();
- }
-}
diff --git a/src/test/java/com/thealgorithms/backtracking/CombinationTest.java b/src/test/java/com/thealgorithms/backtracking/CombinationTest.java
index a9d1163f3ecd..5d2f99ccadf8 100644
--- a/src/test/java/com/thealgorithms/backtracking/CombinationTest.java
+++ b/src/test/java/com/thealgorithms/backtracking/CombinationTest.java
@@ -28,16 +28,16 @@ void testNoElement() {
@Test
void testLengthOne() {
List> result = Combination.combination(new Integer[] {1, 2}, 1);
- assertTrue(result.get(0).iterator().next() == 1);
- assertTrue(result.get(1).iterator().next() == 2);
+ assertEquals(1, result.get(0).iterator().next());
+ assertEquals(2, result.get(1).iterator().next());
}
@Test
void testLengthTwo() {
List> result = Combination.combination(new Integer[] {1, 2}, 2);
Integer[] arr = result.get(0).toArray(new Integer[2]);
- assertTrue(arr[0] == 1);
- assertTrue(arr[1] == 2);
+ assertEquals(1, arr[0]);
+ assertEquals(2, arr[1]);
}
@Test
diff --git a/src/test/java/com/thealgorithms/backtracking/PermutationTest.java b/src/test/java/com/thealgorithms/backtracking/PermutationTest.java
index 76a714829109..54747e5e73a1 100644
--- a/src/test/java/com/thealgorithms/backtracking/PermutationTest.java
+++ b/src/test/java/com/thealgorithms/backtracking/PermutationTest.java
@@ -12,13 +12,13 @@ public class PermutationTest {
@Test
void testNoElement() {
List result = Permutation.permutation(new Integer[] {});
- assertEquals(result.get(0).length, 0);
+ assertEquals(0, result.get(0).length);
}
@Test
void testSingleElement() {
List result = Permutation.permutation(new Integer[] {1});
- assertEquals(result.get(0)[0], 1);
+ assertEquals(1, result.get(0)[0]);
}
@Test
diff --git a/src/test/java/com/thealgorithms/ciphers/ECCTest.java b/src/test/java/com/thealgorithms/ciphers/ECCTest.java
index 701f801af1c8..b78ba51f7c3e 100644
--- a/src/test/java/com/thealgorithms/ciphers/ECCTest.java
+++ b/src/test/java/com/thealgorithms/ciphers/ECCTest.java
@@ -37,7 +37,7 @@ void testEncrypt() {
System.out.println("Base Point G: " + curve.getBasePoint());
// Verify that the ciphertext is not empty
- assertEquals(cipherText.length, 2); // Check if the ciphertext contains two points (R and S)
+ assertEquals(2, cipherText.length); // Check if the ciphertext contains two points (R and S)
// Output the encrypted coordinate points
System.out.println("Encrypted Points:");
diff --git a/src/test/java/com/thealgorithms/ciphers/ElGamalCipherTest.java b/src/test/java/com/thealgorithms/ciphers/ElGamalCipherTest.java
new file mode 100644
index 000000000000..63dec4846bbc
--- /dev/null
+++ b/src/test/java/com/thealgorithms/ciphers/ElGamalCipherTest.java
@@ -0,0 +1,145 @@
+package com.thealgorithms.ciphers;
+
+import java.math.BigInteger;
+import java.util.stream.Stream;
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.MethodSource;
+
+/**
+ * Unit tests for ElGamalCipher.
+ * Includes property-based testing (homomorphism), probabilistic checks,
+ * and boundary validation.
+ */
+class ElGamalCipherTest {
+
+ private static ElGamalCipher.KeyPair sharedKeys;
+
+ @BeforeAll
+ static void setup() {
+ // Generate 256-bit keys for efficient unit testing
+ sharedKeys = ElGamalCipher.generateKeys(256);
+ }
+
+ @Test
+ @DisplayName("Test Key Generation Validity")
+ void testKeyGeneration() {
+ Assertions.assertNotNull(sharedKeys.p());
+ Assertions.assertNotNull(sharedKeys.g());
+ Assertions.assertNotNull(sharedKeys.x());
+ Assertions.assertNotNull(sharedKeys.y());
+
+ // Verify generator bounds: 1 < g < p
+ Assertions.assertTrue(sharedKeys.g().compareTo(BigInteger.ONE) > 0);
+ Assertions.assertTrue(sharedKeys.g().compareTo(sharedKeys.p()) < 0);
+
+ // Verify private key bounds: 1 < x < p-1
+ Assertions.assertTrue(sharedKeys.x().compareTo(BigInteger.ONE) > 0);
+ Assertions.assertTrue(sharedKeys.x().compareTo(sharedKeys.p().subtract(BigInteger.ONE)) < 0);
+ }
+
+ @Test
+ @DisplayName("Security Check: Probabilistic Encryption")
+ void testSemanticSecurity() {
+ // Encrypting the same message twice MUST yield different ciphertexts
+ // due to the random ephemeral key 'k'.
+ BigInteger message = new BigInteger("123456789");
+
+ ElGamalCipher.CipherText c1 = ElGamalCipher.encrypt(message, sharedKeys.p(), sharedKeys.g(), sharedKeys.y());
+ ElGamalCipher.CipherText c2 = ElGamalCipher.encrypt(message, sharedKeys.p(), sharedKeys.g(), sharedKeys.y());
+
+ // Check that the ephemeral keys (and thus 'a' components) were different
+ Assertions.assertNotEquals(c1.a(), c2.a(), "Ciphertexts must be randomized (Semantic Security violation)");
+ Assertions.assertNotEquals(c1.b(), c2.b());
+
+ // But both must decrypt to the original message
+ Assertions.assertEquals(ElGamalCipher.decrypt(c1, sharedKeys.x(), sharedKeys.p()), message);
+ Assertions.assertEquals(ElGamalCipher.decrypt(c2, sharedKeys.x(), sharedKeys.p()), message);
+ }
+
+ @ParameterizedTest
+ @MethodSource("provideMessages")
+ @DisplayName("Parameterized Test: Encrypt and Decrypt various messages")
+ void testEncryptDecrypt(String messageStr) {
+ BigInteger message = new BigInteger(messageStr.getBytes());
+
+ // Skip if message exceeds the test key size (256 bits)
+ if (message.compareTo(sharedKeys.p()) >= 0) {
+ return;
+ }
+
+ ElGamalCipher.CipherText ciphertext = ElGamalCipher.encrypt(message, sharedKeys.p(), sharedKeys.g(), sharedKeys.y());
+ BigInteger decrypted = ElGamalCipher.decrypt(ciphertext, sharedKeys.x(), sharedKeys.p());
+
+ Assertions.assertEquals(message, decrypted, "Decrypted BigInteger must match original");
+ Assertions.assertEquals(messageStr, new String(decrypted.toByteArray()), "Decrypted string must match original");
+ }
+
+ static Stream provideMessages() {
+ return Stream.of("Hello World", "TheAlgorithms", "A", "1234567890", "!@#$%^&*()");
+ }
+
+ @Test
+ @DisplayName("Edge Case: Message equals 0")
+ void testMessageZero() {
+ BigInteger zero = BigInteger.ZERO;
+ ElGamalCipher.CipherText ciphertext = ElGamalCipher.encrypt(zero, sharedKeys.p(), sharedKeys.g(), sharedKeys.y());
+ BigInteger decrypted = ElGamalCipher.decrypt(ciphertext, sharedKeys.x(), sharedKeys.p());
+
+ Assertions.assertEquals(zero, decrypted, "Should successfully encrypt/decrypt zero");
+ }
+
+ @Test
+ @DisplayName("Edge Case: Message equals p-1")
+ void testMessageMaxBound() {
+ BigInteger pMinus1 = sharedKeys.p().subtract(BigInteger.ONE);
+ ElGamalCipher.CipherText ciphertext = ElGamalCipher.encrypt(pMinus1, sharedKeys.p(), sharedKeys.g(), sharedKeys.y());
+ BigInteger decrypted = ElGamalCipher.decrypt(ciphertext, sharedKeys.x(), sharedKeys.p());
+
+ Assertions.assertEquals(pMinus1, decrypted, "Should successfully encrypt/decrypt p-1");
+ }
+
+ @Test
+ @DisplayName("Negative Test: Message >= p should fail")
+ void testMessageTooLarge() {
+ BigInteger tooLarge = sharedKeys.p();
+ Assertions.assertThrows(IllegalArgumentException.class, () -> ElGamalCipher.encrypt(tooLarge, sharedKeys.p(), sharedKeys.g(), sharedKeys.y()));
+ }
+
+ @Test
+ @DisplayName("Negative Test: Decrypt with wrong private key")
+ void testWrongKeyDecryption() {
+ BigInteger message = new BigInteger("99999");
+ ElGamalCipher.CipherText ciphertext = ElGamalCipher.encrypt(message, sharedKeys.p(), sharedKeys.g(), sharedKeys.y());
+
+ // Generate a fake private key
+ BigInteger wrongX = sharedKeys.x().add(BigInteger.ONE);
+
+ BigInteger decrypted = ElGamalCipher.decrypt(ciphertext, wrongX, sharedKeys.p());
+
+ Assertions.assertNotEquals(message, decrypted, "Decryption with wrong key must yield incorrect result");
+ }
+
+ @Test
+ @DisplayName("Property Test: Multiplicative Homomorphism")
+ void testHomomorphism() {
+ BigInteger m1 = new BigInteger("50");
+ BigInteger m2 = BigInteger.TEN; // Fix: Replaced new BigInteger("10") with BigInteger.TEN
+
+ ElGamalCipher.CipherText c1 = ElGamalCipher.encrypt(m1, sharedKeys.p(), sharedKeys.g(), sharedKeys.y());
+ ElGamalCipher.CipherText c2 = ElGamalCipher.encrypt(m2, sharedKeys.p(), sharedKeys.g(), sharedKeys.y());
+
+ // Multiply ciphertexts component-wise: (a1*a2, b1*b2)
+ BigInteger aNew = c1.a().multiply(c2.a()).mod(sharedKeys.p());
+ BigInteger bNew = c1.b().multiply(c2.b()).mod(sharedKeys.p());
+ ElGamalCipher.CipherText cCombined = new ElGamalCipher.CipherText(aNew, bNew);
+
+ BigInteger decrypted = ElGamalCipher.decrypt(cCombined, sharedKeys.x(), sharedKeys.p());
+ BigInteger expected = m1.multiply(m2).mod(sharedKeys.p());
+
+ Assertions.assertEquals(expected, decrypted, "Cipher must satisfy multiplicative homomorphism");
+ }
+}
diff --git a/src/test/java/com/thealgorithms/ciphers/PermutationCipherTest.java b/src/test/java/com/thealgorithms/ciphers/PermutationCipherTest.java
index 4ba6787cc97e..ecb7455c1ba2 100644
--- a/src/test/java/com/thealgorithms/ciphers/PermutationCipherTest.java
+++ b/src/test/java/com/thealgorithms/ciphers/PermutationCipherTest.java
@@ -1,6 +1,7 @@
package com.thealgorithms.ciphers;
import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNull;
import static org.junit.jupiter.api.Assertions.assertThrows;
import org.junit.jupiter.api.Test;
@@ -121,8 +122,8 @@ void testNullString() {
String decrypted = cipher.decrypt(encrypted, key);
// then
- assertEquals(null, encrypted);
- assertEquals(null, decrypted);
+ assertNull(encrypted);
+ assertNull(decrypted);
}
@Test
diff --git a/src/test/java/com/thealgorithms/compression/HuffmanCodingTest.java b/src/test/java/com/thealgorithms/compression/HuffmanCodingTest.java
new file mode 100644
index 000000000000..f919417899db
--- /dev/null
+++ b/src/test/java/com/thealgorithms/compression/HuffmanCodingTest.java
@@ -0,0 +1,110 @@
+package com.thealgorithms.compression;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import org.junit.jupiter.api.Test;
+
+class HuffmanCodingTest {
+
+ @Test
+ void testStandardLifecycle() {
+ String input = "efficiency is key";
+ HuffmanCoding huffman = new HuffmanCoding(input);
+
+ String encoded = huffman.encode(input);
+ assertNotNull(encoded);
+ assertTrue(encoded.matches("[01]+"));
+ assertEquals(input, huffman.decode(encoded));
+ }
+
+ @Test
+ void testNullAndEmptyHandling() {
+ HuffmanCoding huffman = new HuffmanCoding("");
+ assertEquals("", huffman.encode(""));
+ assertEquals("", huffman.decode(""));
+
+ HuffmanCoding huffmanNull = new HuffmanCoding(null);
+ assertEquals("", huffmanNull.encode(null));
+ assertEquals("", huffmanNull.decode(null));
+ }
+
+ @Test
+ void testSingleCharacterEdgeCase() {
+ String input = "aaaaa";
+ HuffmanCoding huffman = new HuffmanCoding(input);
+
+ String encoded = huffman.encode(input);
+ assertEquals("00000", encoded);
+ assertEquals(input, huffman.decode(encoded));
+ }
+
+ @Test
+ void testUnicodeAndSpecialCharacters() {
+ // Tests spacing, symbols, non-latin alphabets, and surrogate pairs (emojis)
+ String input = "Hello, World! π\nLine 2: γγγ«γ‘γ―";
+ HuffmanCoding huffman = new HuffmanCoding(input);
+
+ String encoded = huffman.encode(input);
+ assertEquals(input, huffman.decode(encoded));
+ }
+
+ @Test
+ void testFailFastOnUnseenCharacter() {
+ HuffmanCoding huffman = new HuffmanCoding("abc");
+
+ IllegalArgumentException exception = assertThrows(IllegalArgumentException.class,
+ () -> huffman.encode("abcd") // 'd' was not in the original tree
+ );
+ assertTrue(exception.getMessage().contains("not found in Huffman dictionary"));
+ }
+
+ @Test
+ void testFailFastOnInvalidBinaryCharacter() {
+ HuffmanCoding huffman = new HuffmanCoding("abc");
+ String encoded = huffman.encode("abc");
+
+ // Inject a '2' into the binary stream
+ String corruptedEncoded = encoded + "2";
+
+ IllegalArgumentException exception = assertThrows(IllegalArgumentException.class, () -> huffman.decode(corruptedEncoded));
+ assertTrue(exception.getMessage().contains("contains invalid characters"));
+ }
+
+ @Test
+ void testFailFastOnIncompleteSequence() {
+ HuffmanCoding huffman = new HuffmanCoding("abcd");
+ String encoded = huffman.encode("abc");
+
+ // Truncate the last bit to simulate an incomplete byte/sequence transfer
+ String truncatedEncoded = encoded.substring(0, encoded.length() - 1);
+
+ IllegalArgumentException exception = assertThrows(IllegalArgumentException.class, () -> huffman.decode(truncatedEncoded));
+ assertTrue(exception.getMessage().contains("incomplete sequence"));
+ }
+
+ @Test
+ void testImmutabilityOfDictionary() {
+ HuffmanCoding huffman = new HuffmanCoding("abc");
+ var codes = huffman.getHuffmanCodes();
+
+ assertThrows(UnsupportedOperationException.class, () -> codes.put('z', "0101"));
+ }
+
+ @Test
+ void testStressVolume() {
+ StringBuilder sb = new StringBuilder();
+ // Generate a 100,000 character string
+ for (int i = 0; i < 100000; i++) {
+ sb.append((char) ('a' + (i % 26)));
+ }
+ String largeInput = sb.toString();
+
+ HuffmanCoding huffman = new HuffmanCoding(largeInput);
+ String encoded = huffman.encode(largeInput);
+
+ assertEquals(largeInput, huffman.decode(encoded));
+ }
+}
diff --git a/src/test/java/com/thealgorithms/compression/LZ78Test.java b/src/test/java/com/thealgorithms/compression/LZ78Test.java
index 7889b50b76f3..da1fd8d23318 100644
--- a/src/test/java/com/thealgorithms/compression/LZ78Test.java
+++ b/src/test/java/com/thealgorithms/compression/LZ78Test.java
@@ -1,7 +1,6 @@
package com.thealgorithms.compression;
import static org.junit.jupiter.api.Assertions.assertEquals;
-import static org.junit.jupiter.api.Assertions.assertNotNull;
import static org.junit.jupiter.api.Assertions.assertTrue;
import java.util.List;
@@ -286,7 +285,6 @@ void testTokenStructure() {
// All tokens should have valid indices (>= 0)
for (LZ78.Token token : compressed) {
assertTrue(token.index() >= 0);
- assertNotNull(token.nextChar());
}
String decompressed = LZ78.decompress(compressed);
diff --git a/src/test/java/com/thealgorithms/datastructures/dynamicarray/DynamicArrayTest.java b/src/test/java/com/thealgorithms/datastructures/dynamicarray/DynamicArrayTest.java
index 8fdc93e1ca22..39e3fa0abe77 100644
--- a/src/test/java/com/thealgorithms/datastructures/dynamicarray/DynamicArrayTest.java
+++ b/src/test/java/com/thealgorithms/datastructures/dynamicarray/DynamicArrayTest.java
@@ -255,4 +255,23 @@ public void testCapacityDoubling() {
assertEquals(3, array.getSize());
assertEquals("Charlie", array.get(2));
}
+
+ @Test
+ public void testContains() {
+ DynamicArray array = new DynamicArray<>();
+ array.add(1);
+ array.add(2);
+ array.add(3);
+
+ assertTrue(array.contains(2));
+ assertFalse(array.contains(5));
+ }
+
+ @Test
+ public void testContainsWithNull() {
+ DynamicArray array = new DynamicArray<>();
+ array.add(null);
+
+ assertTrue(array.contains(null));
+ }
}
diff --git a/src/test/java/com/thealgorithms/datastructures/hashmap/hashing/GenericHashMapUsingArrayTest.java b/src/test/java/com/thealgorithms/datastructures/hashmap/hashing/GenericHashMapUsingArrayTest.java
index 5d1733a3e97c..6b6e670a258b 100644
--- a/src/test/java/com/thealgorithms/datastructures/hashmap/hashing/GenericHashMapUsingArrayTest.java
+++ b/src/test/java/com/thealgorithms/datastructures/hashmap/hashing/GenericHashMapUsingArrayTest.java
@@ -1,11 +1,9 @@
package com.thealgorithms.datastructures.hashmap.hashing;
-import static org.junit.jupiter.api.Assertions.assertEquals;
-import static org.junit.jupiter.api.Assertions.assertFalse;
-import static org.junit.jupiter.api.Assertions.assertNotNull;
-import static org.junit.jupiter.api.Assertions.assertTrue;
-
+import org.junit.jupiter.api.Assertions;
import org.junit.jupiter.api.Test;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.ValueSource;
class GenericHashMapUsingArrayTest {
@@ -16,10 +14,10 @@ void testGenericHashmapWhichUsesArrayAndBothKeyAndValueAreStrings() {
map.put("Nepal", "Kathmandu");
map.put("India", "New Delhi");
map.put("Australia", "Sydney");
- assertNotNull(map);
- assertEquals(4, map.size());
- assertEquals("Kathmandu", map.get("Nepal"));
- assertEquals("Sydney", map.get("Australia"));
+ Assertions.assertNotNull(map);
+ Assertions.assertEquals(4, map.size());
+ Assertions.assertEquals("Kathmandu", map.get("Nepal"));
+ Assertions.assertEquals("Sydney", map.get("Australia"));
}
@Test
@@ -29,12 +27,12 @@ void testGenericHashmapWhichUsesArrayAndKeyIsStringValueIsInteger() {
map.put("Nepal", 25);
map.put("India", 101);
map.put("Australia", 99);
- assertNotNull(map);
- assertEquals(4, map.size());
- assertEquals(25, map.get("Nepal"));
- assertEquals(99, map.get("Australia"));
+ Assertions.assertNotNull(map);
+ Assertions.assertEquals(4, map.size());
+ Assertions.assertEquals(25, map.get("Nepal"));
+ Assertions.assertEquals(99, map.get("Australia"));
map.remove("Nepal");
- assertFalse(map.containsKey("Nepal"));
+ Assertions.assertFalse(map.containsKey("Nepal"));
}
@Test
@@ -44,11 +42,11 @@ void testGenericHashmapWhichUsesArrayAndKeyIsIntegerValueIsString() {
map.put(34, "Kathmandu");
map.put(46, "New Delhi");
map.put(89, "Sydney");
- assertNotNull(map);
- assertEquals(4, map.size());
- assertEquals("Sydney", map.get(89));
- assertEquals("Washington DC", map.get(101));
- assertTrue(map.containsKey(46));
+ Assertions.assertNotNull(map);
+ Assertions.assertEquals(4, map.size());
+ Assertions.assertEquals("Sydney", map.get(89));
+ Assertions.assertEquals("Washington DC", map.get(101));
+ Assertions.assertTrue(map.containsKey(46));
}
@Test
@@ -56,7 +54,7 @@ void testRemoveNonExistentKey() {
GenericHashMapUsingArray map = new GenericHashMapUsingArray<>();
map.put("USA", "Washington DC");
map.remove("Nepal"); // Attempting to remove a non-existent key
- assertEquals(1, map.size()); // Size should remain the same
+ Assertions.assertEquals(1, map.size()); // Size should remain the same
}
@Test
@@ -65,8 +63,8 @@ void testRehashing() {
for (int i = 0; i < 20; i++) {
map.put("Key" + i, "Value" + i);
}
- assertEquals(20, map.size()); // Ensure all items were added
- assertEquals("Value5", map.get("Key5")); // Check retrieval after rehash
+ Assertions.assertEquals(20, map.size()); // Ensure all items were added
+ Assertions.assertEquals("Value5", map.get("Key5")); // Check retrieval after rehash
}
@Test
@@ -74,7 +72,7 @@ void testUpdateValueForExistingKey() {
GenericHashMapUsingArray map = new GenericHashMapUsingArray<>();
map.put("USA", "Washington DC");
map.put("USA", "New Washington DC"); // Updating value for existing key
- assertEquals("New Washington DC", map.get("USA"));
+ Assertions.assertEquals("New Washington DC", map.get("USA"));
}
@Test
@@ -83,14 +81,154 @@ void testToStringMethod() {
map.put("USA", "Washington DC");
map.put("Nepal", "Kathmandu");
String expected = "{USA : Washington DC, Nepal : Kathmandu}";
- assertEquals(expected, map.toString());
+ Assertions.assertEquals(expected, map.toString());
}
@Test
void testContainsKey() {
GenericHashMapUsingArray map = new GenericHashMapUsingArray<>();
map.put("USA", "Washington DC");
- assertTrue(map.containsKey("USA"));
- assertFalse(map.containsKey("Nepal"));
+ Assertions.assertTrue(map.containsKey("USA"));
+ Assertions.assertFalse(map.containsKey("Nepal"));
+ }
+
+ // ======= Added tests from the new version =======
+
+ @Test
+ void shouldThrowNullPointerExceptionForNullKey() {
+ GenericHashMapUsingArray map = new GenericHashMapUsingArray<>();
+ String nullKey = null; // Use variable to avoid static analysis false positive
+ Assertions.assertThrows(NullPointerException.class, () -> map.put(nullKey, "value"));
+ }
+
+ @Test
+ void shouldStoreNullValueForKey() {
+ GenericHashMapUsingArray map = new GenericHashMapUsingArray<>();
+ map.put("keyWithNullValue", null);
+ Assertions.assertEquals(1, map.size());
+ Assertions.assertNull(map.get("keyWithNullValue"));
+ // Note: containsKey returns false for null values due to implementation
+ Assertions.assertFalse(map.containsKey("keyWithNullValue"));
+ }
+
+ @Test
+ void shouldHandleCollisionWhenKeysHashToSameBucket() {
+ GenericHashMapUsingArray map = new GenericHashMapUsingArray<>();
+ Integer key1 = 1;
+ Integer key2 = 17;
+ map.put(key1, 100);
+ map.put(key2, 200);
+ Assertions.assertEquals(2, map.size());
+ Assertions.assertEquals(100, map.get(key1));
+ Assertions.assertEquals(200, map.get(key2));
+ Assertions.assertTrue(map.containsKey(key1));
+ Assertions.assertTrue(map.containsKey(key2));
+ }
+
+ @Test
+ void shouldHandleEmptyStringAsKey() {
+ GenericHashMapUsingArray map = new GenericHashMapUsingArray<>();
+ map.put("", "valueForEmptyKey");
+ Assertions.assertEquals(1, map.size());
+ Assertions.assertEquals("valueForEmptyKey", map.get(""));
+ Assertions.assertTrue(map.containsKey(""));
+ }
+
+ @Test
+ void shouldHandleEmptyStringAsValue() {
+ GenericHashMapUsingArray map = new GenericHashMapUsingArray<>();
+ map.put("keyForEmptyValue", "");
+ Assertions.assertEquals(1, map.size());
+ Assertions.assertEquals("", map.get("keyForEmptyValue"));
+ Assertions.assertTrue(map.containsKey("keyForEmptyValue"));
+ }
+
+ @Test
+ void shouldHandleNegativeIntegerKeys() {
+ GenericHashMapUsingArray map = new GenericHashMapUsingArray<>();
+ map.put(-1, 100);
+ map.put(-100, 200);
+ Assertions.assertEquals(2, map.size());
+ Assertions.assertEquals(100, map.get(-1));
+ Assertions.assertEquals(200, map.get(-100));
+ Assertions.assertTrue(map.containsKey(-1));
+ Assertions.assertTrue(map.containsKey(-100));
+ }
+
+ @Test
+ void shouldHandleZeroAsKey() {
+ GenericHashMapUsingArray map = new GenericHashMapUsingArray<>();
+ map.put(0, 100);
+ Assertions.assertEquals(1, map.size());
+ Assertions.assertEquals(100, map.get(0));
+ Assertions.assertTrue(map.containsKey(0));
+ }
+
+ @Test
+ void shouldHandleStringWithSpecialCharacters() {
+ GenericHashMapUsingArray map = new GenericHashMapUsingArray<>();
+ map.put("key!@#$%^&*()", "value<>?/\\|");
+ Assertions.assertEquals(1, map.size());
+ Assertions.assertEquals("value<>?/\\|", map.get("key!@#$%^&*()"));
+ Assertions.assertTrue(map.containsKey("key!@#$%^&*()"));
+ }
+
+ @Test
+ void shouldHandleLongStrings() {
+ GenericHashMapUsingArray map = new GenericHashMapUsingArray<>();
+ StringBuilder longKey = new StringBuilder();
+ StringBuilder longValue = new StringBuilder();
+ for (int i = 0; i < 1000; i++) {
+ longKey.append("a");
+ longValue.append("b");
+ }
+ String key = longKey.toString();
+ String value = longValue.toString();
+ map.put(key, value);
+ Assertions.assertEquals(1, map.size());
+ Assertions.assertEquals(value, map.get(key));
+ Assertions.assertTrue(map.containsKey(key));
+ }
+
+ @ParameterizedTest
+ @ValueSource(strings = {"a", "ab", "abc", "test", "longerString"})
+ void shouldHandleKeysOfDifferentLengths(String key) {
+ GenericHashMapUsingArray map = new GenericHashMapUsingArray<>();
+ map.put(key, "value");
+ Assertions.assertEquals(1, map.size());
+ Assertions.assertEquals("value", map.get(key));
+ Assertions.assertTrue(map.containsKey(key));
+ }
+
+ @Test
+ void shouldHandleUpdateOnExistingKeyInCollisionBucket() {
+ GenericHashMapUsingArray map = new GenericHashMapUsingArray<>();
+ Integer key1 = 1;
+ Integer key2 = 17;
+ map.put(key1, 100);
+ map.put(key2, 200);
+ Assertions.assertEquals(2, map.size());
+ map.put(key2, 999);
+ Assertions.assertEquals(2, map.size());
+ Assertions.assertEquals(100, map.get(key1));
+ Assertions.assertEquals(999, map.get(key2));
+ Assertions.assertTrue(map.containsKey(key1));
+ Assertions.assertTrue(map.containsKey(key2));
+ }
+
+ @Test
+ void shouldHandleExactlyLoadFactorBoundary() {
+ GenericHashMapUsingArray map = new GenericHashMapUsingArray<>();
+ // Fill exactly to load factor (12 items with capacity 16 and 0.75 load factor)
+ for (int i = 0; i < 12; i++) {
+ map.put(i, i * 10);
+ }
+ Assertions.assertEquals(12, map.size());
+ // Act - This should trigger rehash on 13th item
+ map.put(12, 120);
+ // Assert - Rehash should have happened
+ Assertions.assertEquals(13, map.size());
+ Assertions.assertEquals(120, map.get(12));
+ Assertions.assertTrue(map.containsKey(12));
}
}
diff --git a/src/test/java/com/thealgorithms/datastructures/hashmap/hashing/MapTest.java b/src/test/java/com/thealgorithms/datastructures/hashmap/hashing/MapTest.java
index 44551a8adac6..ef7739a2e8a9 100644
--- a/src/test/java/com/thealgorithms/datastructures/hashmap/hashing/MapTest.java
+++ b/src/test/java/com/thealgorithms/datastructures/hashmap/hashing/MapTest.java
@@ -81,19 +81,19 @@ void containsTest() {
@Test
void sizeTest() {
Map map = getMap();
- assertEquals(map.size(), 0);
+ assertEquals(0, map.size());
for (int i = -100; i < 100; i++) {
map.put(i, String.valueOf(i));
}
- assertEquals(map.size(), 200);
+ assertEquals(200, map.size());
for (int i = -50; i < 50; i++) {
map.delete(i);
}
- assertEquals(map.size(), 100);
+ assertEquals(100, map.size());
}
@Test
diff --git a/src/test/java/com/thealgorithms/datastructures/heaps/HeapElementTest.java b/src/test/java/com/thealgorithms/datastructures/heaps/HeapElementTest.java
index d04a9de8a94b..792969200c82 100644
--- a/src/test/java/com/thealgorithms/datastructures/heaps/HeapElementTest.java
+++ b/src/test/java/com/thealgorithms/datastructures/heaps/HeapElementTest.java
@@ -2,6 +2,7 @@
import static org.junit.jupiter.api.Assertions.assertEquals;
import static org.junit.jupiter.api.Assertions.assertNotEquals;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
import static org.junit.jupiter.api.Assertions.assertNull;
import org.junit.jupiter.api.Test;
@@ -39,7 +40,7 @@ void testEquals() {
assertEquals(element1, element2); // Same key and info
assertNotEquals(element1, element3); // Different key
- assertNotEquals(null, element1); // Check for null
+ assertNotNull(element1);
assertNotEquals("String", element1); // Check for different type
}
diff --git a/src/test/java/com/thealgorithms/datastructures/lists/MiddleOfLinkedListTest.java b/src/test/java/com/thealgorithms/datastructures/lists/MiddleOfLinkedListTest.java
new file mode 100644
index 000000000000..ba5614a07916
--- /dev/null
+++ b/src/test/java/com/thealgorithms/datastructures/lists/MiddleOfLinkedListTest.java
@@ -0,0 +1,74 @@
+package com.thealgorithms.datastructures.lists;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNull;
+
+import java.util.Objects;
+import org.junit.jupiter.api.Test;
+
+public class MiddleOfLinkedListTest {
+
+ private static SinglyLinkedListNode listOf(int firstValue, int... remainingValues) {
+ SinglyLinkedListNode head = new SinglyLinkedListNode(firstValue);
+ SinglyLinkedListNode current = head;
+
+ for (int i = 0; i < remainingValues.length; i++) {
+ current.next = new SinglyLinkedListNode(remainingValues[i]);
+ current = current.next;
+ }
+ return head;
+ }
+
+ @Test
+ void middleNodeOddLength() {
+ SinglyLinkedListNode head = listOf(1, 2, 3, 4, 5);
+ SinglyLinkedListNode middle = Objects.requireNonNull(MiddleOfLinkedList.middleNode(head));
+ assertEquals(3, middle.value);
+ }
+
+ @Test
+ void middleNodeEvenLengthReturnsSecondMiddle() {
+ SinglyLinkedListNode head = listOf(1, 2, 3, 4, 5, 6);
+ SinglyLinkedListNode middle = Objects.requireNonNull(MiddleOfLinkedList.middleNode(head));
+ assertEquals(4, middle.value);
+ }
+
+ @Test
+ void middleNodeSingleElement() {
+ SinglyLinkedListNode head = listOf(42);
+ SinglyLinkedListNode middle = Objects.requireNonNull(MiddleOfLinkedList.middleNode(head));
+ assertEquals(42, middle.value);
+ }
+
+ @Test
+ void middleNodeTwoElementsReturnsSecond() {
+ SinglyLinkedListNode head = listOf(10, 20);
+ SinglyLinkedListNode middle = Objects.requireNonNull(MiddleOfLinkedList.middleNode(head));
+ assertEquals(20, middle.value);
+ }
+
+ @Test
+ void middleNodeNullHead() {
+ assertNull(MiddleOfLinkedList.middleNode(null));
+ }
+
+ @Test
+ void middleNodeDoesNotModifyListStructure() {
+ SinglyLinkedListNode first = new SinglyLinkedListNode(1);
+ SinglyLinkedListNode second = new SinglyLinkedListNode(2);
+ SinglyLinkedListNode third = new SinglyLinkedListNode(3);
+ SinglyLinkedListNode fourth = new SinglyLinkedListNode(4);
+
+ first.next = second;
+ second.next = third;
+ third.next = fourth;
+
+ SinglyLinkedListNode middle = Objects.requireNonNull(MiddleOfLinkedList.middleNode(first));
+ assertEquals(3, middle.value);
+
+ assertEquals(second, first.next);
+ assertEquals(third, second.next);
+ assertEquals(fourth, third.next);
+ assertNull(fourth.next);
+ }
+}
diff --git a/src/test/java/com/thealgorithms/datastructures/queues/PriorityQueuesTest.java b/src/test/java/com/thealgorithms/datastructures/queues/PriorityQueuesTest.java
index e97fe091c556..3bb8bbabb761 100644
--- a/src/test/java/com/thealgorithms/datastructures/queues/PriorityQueuesTest.java
+++ b/src/test/java/com/thealgorithms/datastructures/queues/PriorityQueuesTest.java
@@ -9,14 +9,14 @@ class PriorityQueuesTest {
void testPQInsertion() {
PriorityQueue myQueue = new PriorityQueue(4);
myQueue.insert(2);
- Assertions.assertEquals(myQueue.peek(), 2);
+ Assertions.assertEquals(2, myQueue.peek());
myQueue.insert(5);
myQueue.insert(3);
- Assertions.assertEquals(myQueue.peek(), 5);
+ Assertions.assertEquals(5, myQueue.peek());
myQueue.insert(10);
- Assertions.assertEquals(myQueue.peek(), 10);
+ Assertions.assertEquals(10, myQueue.peek());
}
@Test
@@ -28,32 +28,32 @@ void testPQDeletion() {
myQueue.insert(10);
myQueue.remove();
- Assertions.assertEquals(myQueue.peek(), 5);
+ Assertions.assertEquals(5, myQueue.peek());
myQueue.remove();
myQueue.remove();
- Assertions.assertEquals(myQueue.peek(), 2);
+ Assertions.assertEquals(2, myQueue.peek());
}
@Test
void testPQExtra() {
PriorityQueue myQueue = new PriorityQueue(4);
- Assertions.assertEquals(myQueue.isEmpty(), true);
- Assertions.assertEquals(myQueue.isFull(), false);
+ Assertions.assertTrue(myQueue.isEmpty());
+ Assertions.assertFalse(myQueue.isFull());
myQueue.insert(2);
myQueue.insert(5);
- Assertions.assertEquals(myQueue.isFull(), false);
+ Assertions.assertFalse(myQueue.isFull());
myQueue.insert(3);
myQueue.insert(10);
- Assertions.assertEquals(myQueue.isEmpty(), false);
- Assertions.assertEquals(myQueue.isFull(), true);
+ Assertions.assertFalse(myQueue.isEmpty());
+ Assertions.assertTrue(myQueue.isFull());
myQueue.remove();
- Assertions.assertEquals(myQueue.getSize(), 3);
- Assertions.assertEquals(myQueue.peek(), 5);
+ Assertions.assertEquals(3, myQueue.getSize());
+ Assertions.assertEquals(5, myQueue.peek());
myQueue.remove();
myQueue.remove();
- Assertions.assertEquals(myQueue.peek(), 2);
- Assertions.assertEquals(myQueue.getSize(), 1);
+ Assertions.assertEquals(2, myQueue.peek());
+ Assertions.assertEquals(1, myQueue.getSize());
}
@Test
diff --git a/src/test/java/com/thealgorithms/datastructures/queues/ReverseQueueRecursionTest.java b/src/test/java/com/thealgorithms/datastructures/queues/ReverseQueueRecursionTest.java
new file mode 100644
index 000000000000..e3abe15b6a46
--- /dev/null
+++ b/src/test/java/com/thealgorithms/datastructures/queues/ReverseQueueRecursionTest.java
@@ -0,0 +1,54 @@
+package com.thealgorithms.datastructures.queues;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import java.util.LinkedList;
+import java.util.Queue;
+import org.junit.jupiter.api.Test;
+
+class ReverseQueueRecursionTest {
+ @Test
+ void testReverseMultipleElements() {
+ Queue queue = new LinkedList<>();
+ queue.add(1);
+ queue.add(2);
+ queue.add(3);
+ queue.add(4);
+ ReverseQueueRecursion.reverseQueue(queue);
+ assertEquals(4, queue.poll());
+ assertEquals(3, queue.poll());
+ assertEquals(2, queue.poll());
+ assertEquals(1, queue.poll());
+ assertTrue(queue.isEmpty());
+ }
+
+ @Test
+ void testReverseSingleElement() {
+ Queue queue = new LinkedList<>();
+ queue.add(42);
+ ReverseQueueRecursion.reverseQueue(queue);
+ assertEquals(42, queue.poll());
+ assertTrue(queue.isEmpty());
+ }
+
+ @Test
+ void testReverseEmptyQueue() {
+ Queue queue = new LinkedList<>();
+ ReverseQueueRecursion.reverseQueue(queue);
+ assertTrue(queue.isEmpty());
+ }
+
+ @Test
+ void testReverseStringQueue() {
+ Queue queue = new LinkedList<>();
+ queue.add("A");
+ queue.add("B");
+ queue.add("C");
+ ReverseQueueRecursion.reverseQueue(queue);
+ assertEquals("C", queue.poll());
+ assertEquals("B", queue.poll());
+ assertEquals("A", queue.poll());
+ assertTrue(queue.isEmpty());
+ }
+}
diff --git a/src/test/java/com/thealgorithms/datastructures/trees/TreapTest.java b/src/test/java/com/thealgorithms/datastructures/trees/TreapTest.java
index 09ada594faca..52b74a7a1faf 100644
--- a/src/test/java/com/thealgorithms/datastructures/trees/TreapTest.java
+++ b/src/test/java/com/thealgorithms/datastructures/trees/TreapTest.java
@@ -2,6 +2,7 @@
import static org.junit.jupiter.api.Assertions.assertEquals;
import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertNull;
import org.junit.jupiter.api.Test;
@@ -30,7 +31,7 @@ public void searchAndNotFound() {
treap.insert(3);
treap.insert(8);
treap.insert(1);
- assertEquals(null, treap.search(4));
+ assertNull(treap.search(4));
}
@Test
diff --git a/src/test/java/com/thealgorithms/divideandconquer/ClosestPairTest.java b/src/test/java/com/thealgorithms/divideandconquer/ClosestPairTest.java
index 38784228d68e..b25fd796b112 100644
--- a/src/test/java/com/thealgorithms/divideandconquer/ClosestPairTest.java
+++ b/src/test/java/com/thealgorithms/divideandconquer/ClosestPairTest.java
@@ -16,14 +16,6 @@ public void testBuildLocation() {
assertEquals(4.0, point.y);
}
- @Test
- public void testCreateLocation() {
- ClosestPair cp = new ClosestPair(5);
- ClosestPair.Location[] locations = cp.createLocation(5);
- assertNotNull(locations);
- assertEquals(5, locations.length);
- }
-
@Test
public void testXPartition() {
ClosestPair cp = new ClosestPair(5);
diff --git a/src/test/java/com/thealgorithms/dynamicprogramming/LongestCommonSubsequenceTest.java b/src/test/java/com/thealgorithms/dynamicprogramming/LongestCommonSubsequenceTest.java
index 40bbdff15ca6..91169c4cc9d8 100644
--- a/src/test/java/com/thealgorithms/dynamicprogramming/LongestCommonSubsequenceTest.java
+++ b/src/test/java/com/thealgorithms/dynamicprogramming/LongestCommonSubsequenceTest.java
@@ -1,6 +1,7 @@
package com.thealgorithms.dynamicprogramming;
import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNull;
import org.junit.jupiter.api.Test;
@@ -55,27 +56,24 @@ public void testLCSWithBothEmptyStrings() {
public void testLCSWithNullFirstString() {
String str1 = null;
String str2 = "XYZ";
- String expected = null; // Should return null if first string is null
String result = LongestCommonSubsequence.getLCS(str1, str2);
- assertEquals(expected, result);
+ assertNull(result);
}
@Test
public void testLCSWithNullSecondString() {
String str1 = "ABC";
String str2 = null;
- String expected = null; // Should return null if second string is null
String result = LongestCommonSubsequence.getLCS(str1, str2);
- assertEquals(expected, result);
+ assertNull(result);
}
@Test
public void testLCSWithNullBothStrings() {
String str1 = null;
String str2 = null;
- String expected = null; // Should return null if both strings are null
String result = LongestCommonSubsequence.getLCS(str1, str2);
- assertEquals(expected, result);
+ assertNull(result);
}
@Test
diff --git a/src/test/java/com/thealgorithms/io/BufferedReaderTest.java b/src/test/java/com/thealgorithms/io/BufferedReaderTest.java
index 891c3066058e..088e86f8f7c5 100644
--- a/src/test/java/com/thealgorithms/io/BufferedReaderTest.java
+++ b/src/test/java/com/thealgorithms/io/BufferedReaderTest.java
@@ -17,15 +17,15 @@ public void testPeeks() throws IOException {
BufferedReader reader = new BufferedReader(input);
// read the first letter
- assertEquals(reader.read(), 'H');
+ assertEquals('H', reader.read());
len--;
- assertEquals(reader.available(), len);
+ assertEquals(len, reader.available());
// position: H[e]llo!\nWorld!
// reader.read() will be == 'e'
- assertEquals(reader.peek(1), 'l');
- assertEquals(reader.peek(2), 'l'); // second l
- assertEquals(reader.peek(3), 'o');
+ assertEquals('l', reader.peek(1));
+ assertEquals('l', reader.peek(2)); // second l
+ assertEquals('o', reader.peek(3));
}
@Test
@@ -38,21 +38,21 @@ public void testMixes() throws IOException {
BufferedReader reader = new BufferedReader(input);
// read the first letter
- assertEquals(reader.read(), 'H'); // first letter
+ assertEquals('H', reader.read()); // first letter
len--;
- assertEquals(reader.peek(1), 'l'); // third later (second letter after 'H')
- assertEquals(reader.read(), 'e'); // second letter
+ assertEquals('l', reader.peek(1)); // third later (second letter after 'H')
+ assertEquals('e', reader.read()); // second letter
len--;
- assertEquals(reader.available(), len);
+ assertEquals(len, reader.available());
// position: H[e]llo!\nWorld!
- assertEquals(reader.peek(2), 'o'); // second l
- assertEquals(reader.peek(3), '!');
- assertEquals(reader.peek(4), '\n');
+ assertEquals('o', reader.peek(2)); // second l
+ assertEquals('!', reader.peek(3));
+ assertEquals('\n', reader.peek(4));
- assertEquals(reader.read(), 'l'); // third letter
- assertEquals(reader.peek(1), 'o'); // fourth letter
+ assertEquals('l', reader.read()); // third letter
+ assertEquals('o', reader.peek(1)); // fourth letter
for (int i = 0; i < 6; i++) {
reader.read();
@@ -74,23 +74,23 @@ public void testBlockPractical() throws IOException {
ByteArrayInputStream input = new ByteArrayInputStream(bytes);
BufferedReader reader = new BufferedReader(input);
- assertEquals(reader.peek(), 'H');
- assertEquals(reader.read(), '!'); // read the first letter
+ assertEquals('H', reader.peek());
+ assertEquals('!', reader.read()); // read the first letter
len--;
// this only reads the next 5 bytes (Hello) because
// the default buffer size = 5
- assertEquals(new String(reader.readBlock()), "Hello");
+ assertEquals("Hello", new String(reader.readBlock()));
len -= 5;
assertEquals(reader.available(), len);
// maybe kind of a practical demonstration / use case
if (reader.read() == '\n') {
- assertEquals(reader.read(), 'W');
- assertEquals(reader.read(), 'o');
+ assertEquals('W', reader.read());
+ assertEquals('o', reader.read());
// the rest of the blocks
- assertEquals(new String(reader.readBlock()), "rld!");
+ assertEquals("rld!", new String(reader.readBlock()));
} else {
// should not reach
throw new IOException("Something not right");
diff --git a/src/test/java/com/thealgorithms/maths/AreaTest.java b/src/test/java/com/thealgorithms/maths/AreaTest.java
index b28afb85fbc3..1c2fe53ff3f3 100644
--- a/src/test/java/com/thealgorithms/maths/AreaTest.java
+++ b/src/test/java/com/thealgorithms/maths/AreaTest.java
@@ -16,6 +16,11 @@ void testSurfaceAreaCube() {
assertEquals(6.0, Area.surfaceAreaCube(1));
}
+ @Test
+ void testSurfaceAreaCuboid() {
+ assertEquals(214.0, Area.surfaceAreaCuboid(5, 6, 7));
+ }
+
@Test
void testSurfaceAreaSphere() {
assertEquals(12.566370614359172, Area.surfaceAreaSphere(1));
@@ -70,6 +75,12 @@ void surfaceAreaCone() {
void testAllIllegalInput() {
assertAll(()
-> assertThrows(IllegalArgumentException.class, () -> Area.surfaceAreaCube(0)),
+ ()
+ -> assertThrows(IllegalArgumentException.class, () -> Area.surfaceAreaCuboid(0, 1, 2)),
+ ()
+ -> assertThrows(IllegalArgumentException.class, () -> Area.surfaceAreaCuboid(1, 0, 2)),
+ ()
+ -> assertThrows(IllegalArgumentException.class, () -> Area.surfaceAreaCuboid(1, 2, 0)),
()
-> assertThrows(IllegalArgumentException.class, () -> Area.surfaceAreaSphere(0)),
()
diff --git a/src/test/java/com/thealgorithms/maths/BellNumbersTest.java b/src/test/java/com/thealgorithms/maths/BellNumbersTest.java
new file mode 100644
index 000000000000..8dd83cf0f7a9
--- /dev/null
+++ b/src/test/java/com/thealgorithms/maths/BellNumbersTest.java
@@ -0,0 +1,53 @@
+package com.thealgorithms.maths;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+import org.junit.jupiter.api.Test;
+
+class BellNumbersTest {
+
+ @Test
+ void testStandardCases() {
+ // Base cases and small numbers
+ assertEquals(1, BellNumbers.compute(0));
+ assertEquals(1, BellNumbers.compute(1));
+ assertEquals(2, BellNumbers.compute(2));
+ assertEquals(5, BellNumbers.compute(3));
+ assertEquals(15, BellNumbers.compute(4));
+ assertEquals(52, BellNumbers.compute(5));
+ }
+
+ @Test
+ void testMediumNumber() {
+ // B10 = 115,975
+ assertEquals(115975, BellNumbers.compute(10));
+ // B15 = 1,382,958,545
+ assertEquals(1382958545L, BellNumbers.compute(15));
+ }
+
+ @Test
+ void testLargeNumber() {
+ // B20 = 51,724,158,235,372
+ // We use the 'L' suffix to tell Java this is a long literal
+ assertEquals(51724158235372L, BellNumbers.compute(20));
+ }
+
+ @Test
+ void testMaxLongCapacity() {
+ // B25 is the largest Bell number that fits in a Java long (signed 64-bit)
+ // B25 = 4,638,590,332,229,999,353
+ assertEquals(4638590332229999353L, BellNumbers.compute(25));
+ }
+
+ @Test
+ void testNegativeInput() {
+ assertThrows(IllegalArgumentException.class, () -> BellNumbers.compute(-1));
+ }
+
+ @Test
+ void testOverflowProtection() {
+ // We expect an exception if the user asks for the impossible
+ assertThrows(IllegalArgumentException.class, () -> BellNumbers.compute(26));
+ }
+}
diff --git a/src/test/java/com/thealgorithms/maths/ComplexNumberMultiplyTest.java b/src/test/java/com/thealgorithms/maths/ComplexNumberMultiplyTest.java
new file mode 100644
index 000000000000..02e964b53771
--- /dev/null
+++ b/src/test/java/com/thealgorithms/maths/ComplexNumberMultiplyTest.java
@@ -0,0 +1,34 @@
+package com.thealgorithms.maths;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+import org.junit.jupiter.api.Test;
+
+public class ComplexNumberMultiplyTest {
+
+ @Test
+ void testExample() {
+ assertEquals("0+2i", ComplexNumberMultiply.multiply("1+1i", "1+1i"));
+ }
+
+ @Test
+ void testNegative() {
+ assertEquals("0+-2i", ComplexNumberMultiply.multiply("1+-1i", "1+-1i"));
+ }
+
+ @Test
+ void testZero() {
+ assertEquals("0+0i", ComplexNumberMultiply.multiply("0+0i", "5+3i"));
+ }
+
+ @Test
+ void testInvalidFormat() {
+ assertThrows(IllegalArgumentException.class, () -> ComplexNumberMultiply.multiply("1+1", "1+1i"));
+ }
+
+ @Test
+ void testNullInput() {
+ assertThrows(IllegalArgumentException.class, () -> ComplexNumberMultiply.multiply(null, "1+1i"));
+ }
+}
diff --git a/src/test/java/com/thealgorithms/maths/DistanceBetweenTwoPointsTest.java b/src/test/java/com/thealgorithms/maths/DistanceBetweenTwoPointsTest.java
new file mode 100644
index 000000000000..6bd124629740
--- /dev/null
+++ b/src/test/java/com/thealgorithms/maths/DistanceBetweenTwoPointsTest.java
@@ -0,0 +1,23 @@
+package com.thealgorithms.maths;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import org.junit.jupiter.api.Test;
+
+class DistanceBetweenTwoPointsTest {
+
+ @Test
+ void testDistanceSimple() {
+ assertEquals(5.0, DistanceBetweenTwoPoints.calculate(0, 0, 3, 4), 1e-9);
+ }
+
+ @Test
+ void testDistanceNegativeCoordinates() {
+ assertEquals(5.0, DistanceBetweenTwoPoints.calculate(-1, -1, 2, 3), 1e-9);
+ }
+
+ @Test
+ void testSamePoint() {
+ assertEquals(0.0, DistanceBetweenTwoPoints.calculate(2, 2, 2, 2), 1e-9);
+ }
+}
diff --git a/src/test/java/com/thealgorithms/maths/DistanceFormulaTest.java b/src/test/java/com/thealgorithms/maths/DistanceFormulaTest.java
index 3a14b80dd4f9..66f3b7b03938 100644
--- a/src/test/java/com/thealgorithms/maths/DistanceFormulaTest.java
+++ b/src/test/java/com/thealgorithms/maths/DistanceFormulaTest.java
@@ -9,78 +9,78 @@ public class DistanceFormulaTest {
@Test
void euclideanTest1() {
- Assertions.assertEquals(DistanceFormula.euclideanDistance(1, 1, 2, 2), 1.4142135623730951);
+ Assertions.assertEquals(1.4142135623730951, DistanceFormula.euclideanDistance(1, 1, 2, 2));
}
@Test
void euclideanTest2() {
- Assertions.assertEquals(DistanceFormula.euclideanDistance(1, 3, 8, 0), 7.0710678118654755);
+ Assertions.assertEquals(7.0710678118654755, DistanceFormula.euclideanDistance(1, 3, 8, 0));
}
@Test
void euclideanTest3() {
- Assertions.assertEquals(DistanceFormula.euclideanDistance(2.4, 9.1, 55.1, 100), 110.91911467371168);
+ Assertions.assertEquals(110.91911467371168, DistanceFormula.euclideanDistance(2.4, 9.1, 55.1, 100));
}
@Test
void euclideanTest4() {
- Assertions.assertEquals(DistanceFormula.euclideanDistance(1000, 13, 20000, 84), 19022.067605809836);
+ Assertions.assertEquals(19022.067605809836, DistanceFormula.euclideanDistance(1000, 13, 20000, 84));
}
@Test
public void manhattantest1() {
- assertEquals(DistanceFormula.manhattanDistance(1, 2, 3, 4), 4);
+ assertEquals(4, DistanceFormula.manhattanDistance(1, 2, 3, 4));
}
@Test
public void manhattantest2() {
- assertEquals(DistanceFormula.manhattanDistance(6.5, 8.4, 20.1, 13.6), 18.8);
+ assertEquals(18.8, DistanceFormula.manhattanDistance(6.5, 8.4, 20.1, 13.6));
}
@Test
public void manhattanTest3() {
- assertEquals(DistanceFormula.manhattanDistance(10.112, 50, 8, 25.67), 26.442);
+ assertEquals(26.442, DistanceFormula.manhattanDistance(10.112, 50, 8, 25.67));
}
@Test
public void hammingTest1() {
int[] array1 = {1, 1, 1, 1};
int[] array2 = {0, 0, 0, 0};
- assertEquals(DistanceFormula.hammingDistance(array1, array2), 4);
+ assertEquals(4, DistanceFormula.hammingDistance(array1, array2));
}
@Test
public void hammingTest2() {
int[] array1 = {1, 1, 1, 1};
int[] array2 = {1, 1, 1, 1};
- assertEquals(DistanceFormula.hammingDistance(array1, array2), 0);
+ assertEquals(0, DistanceFormula.hammingDistance(array1, array2));
}
@Test
public void hammingTest3() {
int[] array1 = {1, 0, 0, 1, 1, 0, 1, 1, 0};
int[] array2 = {0, 1, 0, 0, 1, 1, 1, 0, 0};
- assertEquals(DistanceFormula.hammingDistance(array1, array2), 5);
+ assertEquals(5, DistanceFormula.hammingDistance(array1, array2));
}
@Test
public void minkowskiTest1() {
double[] array1 = {1, 3, 8, 5};
double[] array2 = {4, 2, 6, 9};
- assertEquals(DistanceFormula.minkowskiDistance(array1, array2, 1), 10);
+ assertEquals(10, DistanceFormula.minkowskiDistance(array1, array2, 1));
}
@Test
public void minkowskiTest2() {
double[] array1 = {1, 3, 8, 5};
double[] array2 = {4, 2, 6, 9};
- assertEquals(DistanceFormula.minkowskiDistance(array1, array2, 2), 5.477225575051661);
+ assertEquals(5.477225575051661, DistanceFormula.minkowskiDistance(array1, array2, 2));
}
@Test
public void minkowskiTest3() {
double[] array1 = {1, 3, 8, 5};
double[] array2 = {4, 2, 6, 9};
- assertEquals(DistanceFormula.minkowskiDistance(array1, array2, 3), 4.641588833612778);
+ assertEquals(4.641588833612778, DistanceFormula.minkowskiDistance(array1, array2, 3));
}
}
diff --git a/src/test/java/com/thealgorithms/maths/FactorialTest.java b/src/test/java/com/thealgorithms/maths/FactorialTest.java
index b38dc45589ee..3ff7097b8113 100644
--- a/src/test/java/com/thealgorithms/maths/FactorialTest.java
+++ b/src/test/java/com/thealgorithms/maths/FactorialTest.java
@@ -11,7 +11,7 @@ public class FactorialTest {
@Test
public void testWhenInvalidInoutProvidedShouldThrowException() {
IllegalArgumentException exception = assertThrows(IllegalArgumentException.class, () -> Factorial.factorial(-1));
- assertEquals(exception.getMessage(), EXCEPTION_MESSAGE);
+ assertEquals(EXCEPTION_MESSAGE, exception.getMessage());
}
@Test
diff --git a/src/test/java/com/thealgorithms/maths/LinearDiophantineEquationsSolverTest.java b/src/test/java/com/thealgorithms/maths/LinearDiophantineEquationsSolverTest.java
index c4205985dbfd..885382e29ca2 100644
--- a/src/test/java/com/thealgorithms/maths/LinearDiophantineEquationsSolverTest.java
+++ b/src/test/java/com/thealgorithms/maths/LinearDiophantineEquationsSolverTest.java
@@ -176,7 +176,7 @@ void testSolutionEquality() {
assertEquals(solution1, solution2);
assertNotEquals(solution3, solution1);
assertEquals(solution1, solution1);
- assertNotEquals(null, solution1);
+ assertNotNull(solution1);
assertNotEquals("string", solution1);
}
@@ -217,7 +217,7 @@ void testGcdSolutionWrapperEquality() {
assertEquals(wrapper1, wrapper2);
assertNotEquals(wrapper3, wrapper1);
assertEquals(wrapper1, wrapper1);
- assertNotEquals(null, wrapper1);
+ assertNotNull(wrapper1);
assertNotEquals("string", wrapper1);
}
diff --git a/src/test/java/com/thealgorithms/maths/MeansTest.java b/src/test/java/com/thealgorithms/maths/MeansTest.java
index deee0a931910..853fdbea3963 100644
--- a/src/test/java/com/thealgorithms/maths/MeansTest.java
+++ b/src/test/java/com/thealgorithms/maths/MeansTest.java
@@ -172,6 +172,53 @@ void testHarmonicMeanWithLinkedList() {
assertEquals(expected, Means.harmonic(numbers), EPSILON);
}
+ // ========== Quadratic Mean Tests ==========
+
+ @Test
+ void testQuadraticMeanThrowsExceptionForEmptyList() {
+ List numbers = new ArrayList<>();
+ IllegalArgumentException exception = assertThrows(IllegalArgumentException.class, () -> Means.quadratic(numbers));
+ assertTrue(exception.getMessage().contains("Empty list"));
+ }
+
+ @Test
+ void testQuadraticMeanSingleNumber() {
+ LinkedHashSet numbers = new LinkedHashSet<>(Arrays.asList(2.5));
+ assertEquals(2.5, Means.quadratic(numbers), EPSILON);
+ }
+
+ @Test
+ void testQuadraticMeanTwoNumbers() {
+ List numbers = Arrays.asList(1.0, 7.0);
+ assertEquals(5.0, Means.quadratic(numbers), EPSILON);
+ }
+
+ @Test
+ void testQuadraticMeanMultipleNumbers() {
+ Vector numbers = new Vector<>(Arrays.asList(1.0, 2.5, 3.0, 7.5, 10.0));
+ double expected = Math.sqrt(34.5);
+ assertEquals(expected, Means.quadratic(numbers), EPSILON);
+ }
+
+ @Test
+ void testQuadraticMeanThreeNumbers() {
+ List numbers = Arrays.asList(3.0, 6.0, 9.0);
+ double expected = Math.sqrt(42.0);
+ assertEquals(expected, Means.quadratic(numbers), EPSILON);
+ }
+
+ @Test
+ void testQuadraticMeanIdenticalNumbers() {
+ List numbers = Arrays.asList(5.0, 5.0, 5.0);
+ assertEquals(5.0, Means.quadratic(numbers), EPSILON);
+ }
+
+ @Test
+ void testQuadraticMeanWithLinkedList() {
+ LinkedList numbers = new LinkedList<>(Arrays.asList(1.0, 5.0, 11.0));
+ assertEquals(7.0, Means.quadratic(numbers), EPSILON);
+ }
+
// ========== Additional Edge Case Tests ==========
@Test
@@ -198,21 +245,25 @@ void testAllMeansConsistencyForIdenticalValues() {
double arithmetic = Means.arithmetic(numbers);
double geometric = Means.geometric(numbers);
double harmonic = Means.harmonic(numbers);
+ double quadratic = Means.quadratic(numbers);
assertEquals(7.5, arithmetic, EPSILON);
assertEquals(7.5, geometric, EPSILON);
assertEquals(7.5, harmonic, EPSILON);
+ assertEquals(7.5, quadratic, EPSILON);
}
@Test
void testMeansRelationship() {
- // For positive numbers, harmonic mean β€ geometric mean β€ arithmetic mean
+ // For positive numbers, harmonic mean β€ geometric mean β€ arithmetic mean β€ quadratic mean
List numbers = Arrays.asList(2.0, 4.0, 8.0);
double arithmetic = Means.arithmetic(numbers);
double geometric = Means.geometric(numbers);
double harmonic = Means.harmonic(numbers);
+ double quadratic = Means.quadratic(numbers);
assertTrue(harmonic <= geometric, "Harmonic mean should be β€ geometric mean");
assertTrue(geometric <= arithmetic, "Geometric mean should be β€ arithmetic mean");
+ assertTrue(arithmetic <= quadratic, "Arithmetic mean should be β€ quadratic mean");
}
}
diff --git a/src/test/java/com/thealgorithms/maths/NthUglyNumberTest.java b/src/test/java/com/thealgorithms/maths/NthUglyNumberTest.java
index 3fe58dadf8a5..1ee437b190c5 100644
--- a/src/test/java/com/thealgorithms/maths/NthUglyNumberTest.java
+++ b/src/test/java/com/thealgorithms/maths/NthUglyNumberTest.java
@@ -48,22 +48,22 @@ public void testGetWithSameObject() {
var uglyNumbers = new NthUglyNumber(new int[] {7, 2, 5, 3});
for (final var tc : testCases.entrySet()) {
- assertEquals(uglyNumbers.get(tc.getKey()), tc.getValue());
+ assertEquals(tc.getValue(), uglyNumbers.get(tc.getKey()));
}
- assertEquals(uglyNumbers.get(999), 385875);
+ assertEquals(385875, uglyNumbers.get(999));
}
@Test
public void testGetWithBase1() {
var uglyNumbers = new NthUglyNumber(new int[] {1});
- assertEquals(uglyNumbers.get(10), 1);
+ assertEquals(1, uglyNumbers.get(10));
}
@Test
public void testGetWithBase2() {
var uglyNumbers = new NthUglyNumber(new int[] {2});
- assertEquals(uglyNumbers.get(5), 32);
+ assertEquals(32, uglyNumbers.get(5));
}
@Test
diff --git a/src/test/java/com/thealgorithms/maths/PalindromeNumberTest.java b/src/test/java/com/thealgorithms/maths/PalindromeNumberTest.java
index a70100c0b913..4e4bd85d07b5 100644
--- a/src/test/java/com/thealgorithms/maths/PalindromeNumberTest.java
+++ b/src/test/java/com/thealgorithms/maths/PalindromeNumberTest.java
@@ -25,6 +25,6 @@ public void testNumbersAreNotPalindromes() {
@Test
public void testIfNegativeInputThenExceptionExpected() {
IllegalArgumentException exception = Assertions.assertThrows(IllegalArgumentException.class, () -> PalindromeNumber.isPalindrome(-1));
- Assertions.assertEquals(exception.getMessage(), "Input parameter must not be negative!");
+ Assertions.assertEquals("Input parameter must not be negative!", exception.getMessage());
}
}
diff --git a/src/test/java/com/thealgorithms/maths/ParseIntegerTest.java b/src/test/java/com/thealgorithms/maths/ParseIntegerTest.java
index 7649e21eb231..a9b78be88042 100644
--- a/src/test/java/com/thealgorithms/maths/ParseIntegerTest.java
+++ b/src/test/java/com/thealgorithms/maths/ParseIntegerTest.java
@@ -14,13 +14,13 @@ public class ParseIntegerTest {
@Test
public void testNullInput() {
IllegalArgumentException exception = Assertions.assertThrows(IllegalArgumentException.class, () -> ParseInteger.parseInt(null));
- Assertions.assertEquals(exception.getMessage(), NULL_PARAMETER_MESSAGE);
+ Assertions.assertEquals(NULL_PARAMETER_MESSAGE, exception.getMessage());
}
@Test
public void testEmptyInput() {
IllegalArgumentException exception = Assertions.assertThrows(IllegalArgumentException.class, () -> ParseInteger.parseInt(""));
- Assertions.assertEquals(exception.getMessage(), EMPTY_PARAMETER_MESSAGE);
+ Assertions.assertEquals(EMPTY_PARAMETER_MESSAGE, exception.getMessage());
}
@Test
diff --git a/src/test/java/com/thealgorithms/maths/QuadraticEquationSolverTest.java b/src/test/java/com/thealgorithms/maths/QuadraticEquationSolverTest.java
index a2046511ddf5..a6552d56783c 100644
--- a/src/test/java/com/thealgorithms/maths/QuadraticEquationSolverTest.java
+++ b/src/test/java/com/thealgorithms/maths/QuadraticEquationSolverTest.java
@@ -14,10 +14,10 @@ public void testSolveEquationRealRoots() {
double c = 1.9;
ComplexNumber[] roots = quadraticEquationSolver.solveEquation(a, b, c);
- Assertions.assertEquals(roots.length, 2);
- Assertions.assertEquals(roots[0].real, -0.27810465435684306);
+ Assertions.assertEquals(2, roots.length, 2);
+ Assertions.assertEquals(-0.27810465435684306, roots[0].real);
Assertions.assertNull(roots[0].imaginary);
- Assertions.assertEquals(roots[1].real, -1.6266572504050616);
+ Assertions.assertEquals(-1.6266572504050616, roots[1].real);
Assertions.assertNull(roots[1].imaginary);
}
@@ -29,8 +29,8 @@ public void testSolveEquationEqualRoots() {
double c = 1;
ComplexNumber[] roots = quadraticEquationSolver.solveEquation(a, b, c);
- Assertions.assertEquals(roots.length, 1);
- Assertions.assertEquals(roots[0].real, -1);
+ Assertions.assertEquals(1, roots.length);
+ Assertions.assertEquals(-1, roots[0].real);
}
@Test
@@ -41,10 +41,10 @@ public void testSolveEquationComplexRoots() {
double c = 5.6;
ComplexNumber[] roots = quadraticEquationSolver.solveEquation(a, b, c);
- Assertions.assertEquals(roots.length, 2);
- Assertions.assertEquals(roots[0].real, -0.8695652173913044);
- Assertions.assertEquals(roots[0].imaginary, 1.2956229935435948);
- Assertions.assertEquals(roots[1].real, -0.8695652173913044);
- Assertions.assertEquals(roots[1].imaginary, -1.2956229935435948);
+ Assertions.assertEquals(2, roots.length);
+ Assertions.assertEquals(-0.8695652173913044, roots[0].real);
+ Assertions.assertEquals(1.2956229935435948, roots[0].imaginary);
+ Assertions.assertEquals(-0.8695652173913044, roots[1].real);
+ Assertions.assertEquals(-1.2956229935435948, roots[1].imaginary);
}
}
diff --git a/src/test/java/com/thealgorithms/maths/SecondMinMaxTest.java b/src/test/java/com/thealgorithms/maths/SecondMinMaxTest.java
index c744614e5cfa..c5d47f2213a9 100644
--- a/src/test/java/com/thealgorithms/maths/SecondMinMaxTest.java
+++ b/src/test/java/com/thealgorithms/maths/SecondMinMaxTest.java
@@ -29,19 +29,19 @@ public TestCase(final int[] inInputArray, final int inSecondMin, final int inSec
@Test
public void testForEmptyInputArray() {
IllegalArgumentException exception = assertThrows(IllegalArgumentException.class, () -> SecondMinMax.findSecondMin(new int[] {}));
- assertEquals(exception.getMessage(), EXP_MSG_ARR_LEN_LESS_2);
+ assertEquals(EXP_MSG_ARR_LEN_LESS_2, exception.getMessage());
}
@Test
public void testForArrayWithSingleElement() {
IllegalArgumentException exception = assertThrows(IllegalArgumentException.class, () -> SecondMinMax.findSecondMax(new int[] {1}));
- assertEquals(exception.getMessage(), EXP_MSG_ARR_LEN_LESS_2);
+ assertEquals(EXP_MSG_ARR_LEN_LESS_2, exception.getMessage());
}
@Test
public void testForArrayWithSameElements() {
IllegalArgumentException exception = assertThrows(IllegalArgumentException.class, () -> SecondMinMax.findSecondMin(new int[] {1, 1, 1, 1}));
- assertEquals(exception.getMessage(), EXP_MSG_ARR_SAME_ELE);
+ assertEquals(EXP_MSG_ARR_SAME_ELE, exception.getMessage());
}
@ParameterizedTest
diff --git a/src/test/java/com/thealgorithms/maths/StandardDeviationTest.java b/src/test/java/com/thealgorithms/maths/StandardDeviationTest.java
index 2c10d2d14f3e..4716d389a4ca 100644
--- a/src/test/java/com/thealgorithms/maths/StandardDeviationTest.java
+++ b/src/test/java/com/thealgorithms/maths/StandardDeviationTest.java
@@ -8,19 +8,19 @@ public class StandardDeviationTest {
@Test
void test1() {
double[] t1 = new double[] {1, 1, 1, 1, 1};
- Assertions.assertEquals(StandardDeviation.stdDev(t1), 0.0);
+ Assertions.assertEquals(0.0, StandardDeviation.stdDev(t1));
}
@Test
void test2() {
double[] t2 = new double[] {1, 2, 3, 4, 5, 6, 7, 8, 9, 10};
- Assertions.assertEquals(StandardDeviation.stdDev(t2), 2.8722813232690143);
+ Assertions.assertEquals(2.8722813232690143, StandardDeviation.stdDev(t2));
}
@Test
void test3() {
double[] t3 = new double[] {1.1, 8.5, 20.3, 2.4, 6.2};
- Assertions.assertEquals(StandardDeviation.stdDev(t3), 6.8308125431752265);
+ Assertions.assertEquals(6.8308125431752265, StandardDeviation.stdDev(t3));
}
@Test
@@ -32,6 +32,6 @@ void test4() {
100.00045,
56.7,
};
- Assertions.assertEquals(StandardDeviation.stdDev(t4), 38.506117353865775);
+ Assertions.assertEquals(38.506117353865775, StandardDeviation.stdDev(t4));
}
}
diff --git a/src/test/java/com/thealgorithms/maths/StandardScoreTest.java b/src/test/java/com/thealgorithms/maths/StandardScoreTest.java
index 436b1fd011c6..6858b87ad2c6 100644
--- a/src/test/java/com/thealgorithms/maths/StandardScoreTest.java
+++ b/src/test/java/com/thealgorithms/maths/StandardScoreTest.java
@@ -7,21 +7,21 @@ public class StandardScoreTest {
@Test
void test1() {
- Assertions.assertEquals(StandardScore.zScore(2, 0, 5), 0.4);
+ Assertions.assertEquals(0.4, StandardScore.zScore(2, 0, 5));
}
@Test
void test2() {
- Assertions.assertEquals(StandardScore.zScore(1, 1, 1), 0.0);
+ Assertions.assertEquals(0.0, StandardScore.zScore(1, 1, 1));
}
@Test
void test3() {
- Assertions.assertEquals(StandardScore.zScore(2.5, 1.8, 0.7), 1.0);
+ Assertions.assertEquals(1.0, StandardScore.zScore(2.5, 1.8, 0.7));
}
@Test
void test4() {
- Assertions.assertEquals(StandardScore.zScore(8.9, 3, 4.2), 1.4047619047619049);
+ Assertions.assertEquals(1.4047619047619049, StandardScore.zScore(8.9, 3, 4.2));
}
}
diff --git a/src/test/java/com/thealgorithms/maths/VolumeTest.java b/src/test/java/com/thealgorithms/maths/VolumeTest.java
index 7cd0c6716147..c159d7566b46 100644
--- a/src/test/java/com/thealgorithms/maths/VolumeTest.java
+++ b/src/test/java/com/thealgorithms/maths/VolumeTest.java
@@ -1,6 +1,6 @@
package com.thealgorithms.maths;
-import static org.junit.jupiter.api.Assertions.assertTrue;
+import static org.junit.jupiter.api.Assertions.assertEquals;
import org.junit.jupiter.api.Test;
@@ -10,30 +10,36 @@ public class VolumeTest {
public void volume() {
/* test cube */
- assertTrue(Volume.volumeCube(7) == 343.0);
+ assertEquals(343.0, Volume.volumeCube(7));
/* test cuboid */
- assertTrue(Volume.volumeCuboid(2, 5, 7) == 70.0);
+ assertEquals(70.0, Volume.volumeCuboid(2, 5, 7));
/* test sphere */
- assertTrue(Volume.volumeSphere(7) == 1436.7550402417319);
+ assertEquals(1436.7550402417319, Volume.volumeSphere(7));
/* test cylinder */
- assertTrue(Volume.volumeCylinder(3, 7) == 197.92033717615698);
+ assertEquals(197.92033717615698, Volume.volumeCylinder(3, 7));
/* test hemisphere */
- assertTrue(Volume.volumeHemisphere(7) == 718.3775201208659);
+ assertEquals(718.3775201208659, Volume.volumeHemisphere(7));
/* test cone */
- assertTrue(Volume.volumeCone(3, 7) == 65.97344572538566);
+ assertEquals(65.97344572538566, Volume.volumeCone(3, 7));
/* test prism */
- assertTrue(Volume.volumePrism(10, 2) == 20.0);
+ assertEquals(20.0, Volume.volumePrism(10, 2));
/* test pyramid */
- assertTrue(Volume.volumePyramid(10, 3) == 10.0);
+ assertEquals(10.0, Volume.volumePyramid(10, 3));
/* test frustum */
- assertTrue(Volume.volumeFrustumOfCone(3, 5, 7) == 359.188760060433);
+ assertEquals(359.188760060433, Volume.volumeFrustumOfCone(3, 5, 7));
+
+ /* test pyramid frustum */
+ assertEquals(140.0, Volume.volumeFrustumOfPyramid(6, 24, 10));
+
+ /* test torus */
+ assertEquals(39.47841760435743, Volume.volumeTorus(2, 1));
}
}
diff --git a/src/test/java/com/thealgorithms/misc/MedianOfRunningArrayTest.java b/src/test/java/com/thealgorithms/misc/MedianOfRunningArrayTest.java
index f41953035846..c4a74af0ba8b 100644
--- a/src/test/java/com/thealgorithms/misc/MedianOfRunningArrayTest.java
+++ b/src/test/java/com/thealgorithms/misc/MedianOfRunningArrayTest.java
@@ -17,7 +17,7 @@ public class MedianOfRunningArrayTest {
public void testWhenInvalidInoutProvidedShouldThrowException() {
var stream = new MedianOfRunningArrayInteger();
IllegalArgumentException exception = assertThrows(IllegalArgumentException.class, stream::getMedian);
- assertEquals(exception.getMessage(), EXCEPTION_MESSAGE);
+ assertEquals(EXCEPTION_MESSAGE, exception.getMessage());
}
@Test
diff --git a/src/test/java/com/thealgorithms/misc/ShuffleArrayTest.java b/src/test/java/com/thealgorithms/misc/ShuffleArrayTest.java
index 915b83e376b6..c1adafa18d9f 100644
--- a/src/test/java/com/thealgorithms/misc/ShuffleArrayTest.java
+++ b/src/test/java/com/thealgorithms/misc/ShuffleArrayTest.java
@@ -1,6 +1,7 @@
package com.thealgorithms.misc;
import static org.junit.jupiter.api.Assertions.assertArrayEquals;
+import static org.junit.jupiter.api.Assertions.assertEquals;
import static org.junit.jupiter.api.Assertions.assertNotEquals;
import static org.junit.jupiter.api.Assertions.assertTrue;
@@ -67,7 +68,7 @@ void testShuffleRetainsElements() {
ShuffleArray.shuffle(arr);
// Check that the shuffled array contains the same elements
- assertTrue(arr.length == 5);
+ assertEquals(5, arr.length);
for (int i = 1; i <= 5; i++) {
assertTrue(contains(arr, i));
}
diff --git a/src/test/java/com/thealgorithms/others/NewManShanksPrimeTest.java b/src/test/java/com/thealgorithms/others/NewManShanksPrimeTest.java
deleted file mode 100644
index 3b657e441b1c..000000000000
--- a/src/test/java/com/thealgorithms/others/NewManShanksPrimeTest.java
+++ /dev/null
@@ -1,49 +0,0 @@
-package com.thealgorithms.others;
-
-import static org.junit.jupiter.api.Assertions.assertTrue;
-
-import com.thealgorithms.dynamicprogramming.NewManShanksPrime;
-import org.junit.jupiter.api.Test;
-
-public class NewManShanksPrimeTest {
-
- @Test
- void testOne() {
- assertTrue(NewManShanksPrime.nthManShanksPrime(1, 1));
- }
-
- @Test
- void testTwo() {
- assertTrue(NewManShanksPrime.nthManShanksPrime(2, 3));
- }
-
- @Test
- void testThree() {
- assertTrue(NewManShanksPrime.nthManShanksPrime(3, 7));
- }
-
- @Test
- void testFour() {
- assertTrue(NewManShanksPrime.nthManShanksPrime(4, 17));
- }
-
- @Test
- void testFive() {
- assertTrue(NewManShanksPrime.nthManShanksPrime(5, 41));
- }
-
- @Test
- void testSix() {
- assertTrue(NewManShanksPrime.nthManShanksPrime(6, 99));
- }
-
- @Test
- void testSeven() {
- assertTrue(NewManShanksPrime.nthManShanksPrime(7, 239));
- }
-
- @Test
- void testEight() {
- assertTrue(NewManShanksPrime.nthManShanksPrime(8, 577));
- }
-}
diff --git a/src/test/java/com/thealgorithms/others/PasswordGenTest.java b/src/test/java/com/thealgorithms/others/PasswordGenTest.java
index 76492556e75f..4dcdf6b9cf4f 100644
--- a/src/test/java/com/thealgorithms/others/PasswordGenTest.java
+++ b/src/test/java/com/thealgorithms/others/PasswordGenTest.java
@@ -17,7 +17,7 @@ public void failGenerationWithSameMinMaxLengthTest() {
@Test
public void generateOneCharacterPassword() {
String tempPassword = PasswordGen.generatePassword(1, 2);
- assertTrue(tempPassword.length() == 1);
+ assertEquals(1, tempPassword.length());
}
@Test
diff --git a/src/test/java/com/thealgorithms/others/cn/HammingDistanceTest.java b/src/test/java/com/thealgorithms/others/cn/HammingDistanceTest.java
deleted file mode 100644
index 669f928cd247..000000000000
--- a/src/test/java/com/thealgorithms/others/cn/HammingDistanceTest.java
+++ /dev/null
@@ -1,82 +0,0 @@
-package com.thealgorithms.others.cn;
-
-import org.assertj.core.api.Assertions;
-import org.junit.jupiter.api.Test;
-
-public class HammingDistanceTest {
- @Test
- public void checkForDifferentBits() {
- int answer = HammingDistance.compute("000", "011");
- Assertions.assertThat(answer).isEqualTo(2);
- }
-
- /*
-
- 1 0 1 0 1
- 1 1 1 1 0
- ----------
- 0 1 0 1 1
-
-
- */
- @Test
- public void checkForDifferentBitsLength() {
- int answer = HammingDistance.compute("10101", "11110");
- Assertions.assertThat(answer).isEqualTo(3);
- }
-
- @Test
- public void checkForSameBits() {
- String someBits = "111";
- int answer = HammingDistance.compute(someBits, someBits);
- Assertions.assertThat(answer).isEqualTo(0);
- }
-
- @Test
- public void checkForLongDataBits() {
- int answer = HammingDistance.compute("10010101101010000100110100", "00110100001011001100110101");
- Assertions.assertThat(answer).isEqualTo(7);
- }
-
- @Test
- public void mismatchDataBits() {
- Exception ex = org.junit.jupiter.api.Assertions.assertThrows(IllegalArgumentException.class, () -> { HammingDistance.compute("100010", "00011"); });
-
- Assertions.assertThat(ex.getMessage()).contains("must have the same length");
- }
-
- @Test
- public void mismatchDataBits2() {
- Exception ex = org.junit.jupiter.api.Assertions.assertThrows(IllegalArgumentException.class, () -> { HammingDistance.compute("1", "11"); });
-
- Assertions.assertThat(ex.getMessage()).contains("must have the same length");
- }
-
- @Test
- public void checkForLongDataBitsSame() {
- String someBits = "10010101101010000100110100";
- int answer = HammingDistance.compute(someBits, someBits);
- Assertions.assertThat(answer).isEqualTo(0);
- }
-
- @Test
- public void checkForEmptyInput() {
- String someBits = "";
- int answer = HammingDistance.compute(someBits, someBits);
- Assertions.assertThat(answer).isEqualTo(0);
- }
-
- @Test
- public void checkForInputOfLength1() {
- String someBits = "0";
- int answer = HammingDistance.compute(someBits, someBits);
- Assertions.assertThat(answer).isEqualTo(0);
- }
-
- @Test
- public void computeThrowsExceptionWhenInputsAreNotBitStrs() {
- Exception ex = org.junit.jupiter.api.Assertions.assertThrows(IllegalArgumentException.class, () -> { HammingDistance.compute("1A", "11"); });
-
- Assertions.assertThat(ex.getMessage()).contains("must be a binary string");
- }
-}
diff --git a/src/test/java/com/thealgorithms/prefixsum/DifferenceArrayTest.java b/src/test/java/com/thealgorithms/prefixsum/DifferenceArrayTest.java
new file mode 100644
index 000000000000..88a480f25f1a
--- /dev/null
+++ b/src/test/java/com/thealgorithms/prefixsum/DifferenceArrayTest.java
@@ -0,0 +1,110 @@
+package com.thealgorithms.prefixsum;
+
+import static org.junit.jupiter.api.Assertions.assertArrayEquals;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+import org.junit.jupiter.api.Test;
+
+class DifferenceArrayTest {
+
+ @Test
+ void testStandardRangeUpdate() {
+ int[] input = {10, 20, 30, 40, 50};
+ DifferenceArray da = new DifferenceArray(input);
+
+ da.update(1, 3, 5);
+
+ long[] expected = {10, 25, 35, 45, 50};
+ assertArrayEquals(expected, da.getResultArray());
+ }
+
+ @Test
+ void testMultipleOverlappingUpdates() {
+ int[] input = {10, 10, 10, 10, 10};
+ DifferenceArray da = new DifferenceArray(input);
+
+ da.update(0, 2, 10);
+ da.update(2, 4, 20);
+
+ long[] expected = {20, 20, 40, 30, 30};
+ assertArrayEquals(expected, da.getResultArray());
+ }
+
+ @Test
+ void testIntegerOverflowSafety() {
+ int[] input = {Integer.MAX_VALUE, 100};
+ DifferenceArray da = new DifferenceArray(input);
+
+ da.update(0, 0, 100);
+
+ long[] result = da.getResultArray();
+ long expectedVal = (long) Integer.MAX_VALUE + 100;
+
+ assertEquals(expectedVal, result[0]);
+ }
+
+ @Test
+ void testFullRangeUpdate() {
+ int[] input = {1, 2, 3};
+ DifferenceArray da = new DifferenceArray(input);
+
+ da.update(0, 2, 100);
+
+ long[] expected = {101, 102, 103};
+ assertArrayEquals(expected, da.getResultArray());
+ }
+
+ @Test
+ void testBoundaryWriteOptimization() {
+ int[] input = {5, 5};
+ DifferenceArray da = new DifferenceArray(input);
+
+ da.update(1, 1, 5);
+
+ long[] expected = {5, 10};
+
+ assertArrayEquals(expected, da.getResultArray());
+ }
+
+ @Test
+ void testLargeMassiveUpdate() {
+ int[] input = {0};
+ DifferenceArray da = new DifferenceArray(input);
+
+ int iterations = 100000;
+ for (int i = 0; i < iterations; i++) {
+ da.update(0, 0, 1);
+ }
+
+ assertEquals(100000L, da.getResultArray()[0]);
+ }
+
+ @Test
+ void testNullInputThrowsException() {
+ assertThrows(IllegalArgumentException.class, () -> new DifferenceArray(null));
+ }
+
+ @Test
+ void testEmptyInputThrowsException() {
+ assertThrows(IllegalArgumentException.class, () -> new DifferenceArray(new int[] {}));
+ }
+
+ @Test
+ void testInvalidRangeNegativeIndex() {
+ DifferenceArray da = new DifferenceArray(new int[] {1, 2, 3});
+ assertThrows(IllegalArgumentException.class, () -> da.update(-1, 1, 5));
+ }
+
+ @Test
+ void testInvalidRangeOutOfBounds() {
+ DifferenceArray da = new DifferenceArray(new int[] {1, 2, 3});
+ assertThrows(IllegalArgumentException.class, () -> da.update(0, 3, 5));
+ }
+
+ @Test
+ void testInvalidRangeStartGreaterThanEnd() {
+ DifferenceArray da = new DifferenceArray(new int[] {1, 2, 3});
+ assertThrows(IllegalArgumentException.class, () -> da.update(2, 1, 5));
+ }
+}
diff --git a/src/test/java/com/thealgorithms/prefixsum/PrefixSum2DTest.java b/src/test/java/com/thealgorithms/prefixsum/PrefixSum2DTest.java
new file mode 100644
index 000000000000..87feff859356
--- /dev/null
+++ b/src/test/java/com/thealgorithms/prefixsum/PrefixSum2DTest.java
@@ -0,0 +1,92 @@
+package com.thealgorithms.prefixsum;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+
+class PrefixSum2DTest {
+
+ @Test
+ @DisplayName("Test basic 3x3 square matrix")
+ void testStandardSquare() {
+ int[][] matrix = {{1, 2, 3}, {4, 5, 6}, {7, 8, 9}};
+ PrefixSum2D ps = new PrefixSum2D(matrix);
+
+ // Sum of top-left 2x2: {1,2, 4,5} -> 12
+ assertEquals(12L, ps.sumRegion(0, 0, 1, 1));
+ // Sum of bottom-right 2x2: {5,6, 8,9} -> 28
+ assertEquals(28L, ps.sumRegion(1, 1, 2, 2));
+ // Full matrix -> 45
+ assertEquals(45L, ps.sumRegion(0, 0, 2, 2));
+ }
+
+ @Test
+ @DisplayName("Test rectangular matrix (more cols than rows)")
+ void testRectangularWide() {
+ int[][] matrix = {{1, 1, 1, 1}, {2, 2, 2, 2}};
+ PrefixSum2D ps = new PrefixSum2D(matrix);
+
+ // Sum of first 3 columns of both rows -> (1*3) + (2*3) = 9
+ assertEquals(9L, ps.sumRegion(0, 0, 1, 2));
+ }
+
+ @Test
+ @DisplayName("Test rectangular matrix (more rows than cols)")
+ void testRectangularTall() {
+ int[][] matrix = {{1}, {2}, {3}, {4}};
+ PrefixSum2D ps = new PrefixSum2D(matrix);
+
+ // Sum of middle two elements -> 2+3 = 5
+ assertEquals(5L, ps.sumRegion(1, 0, 2, 0));
+ }
+
+ @Test
+ @DisplayName("Test single element matrix")
+ void testSingleElement() {
+ int[][] matrix = {{100}};
+ PrefixSum2D ps = new PrefixSum2D(matrix);
+
+ assertEquals(100L, ps.sumRegion(0, 0, 0, 0));
+ }
+
+ @Test
+ @DisplayName("Test large numbers for overflow (Integer -> Long)")
+ void testLargeNumbers() {
+ // 2 billion. Two of these sum to > MAX_INT
+ int val = 2_000_000_000;
+ int[][] matrix = {{val, val}, {val, val}};
+ PrefixSum2D ps = new PrefixSum2D(matrix);
+
+ // 4 * 2B = 8 Billion
+ assertEquals(8_000_000_000L, ps.sumRegion(0, 0, 1, 1));
+ }
+
+ @Test
+ @DisplayName("Test invalid inputs")
+ void testInvalidInputs() {
+ assertThrows(IllegalArgumentException.class, () -> new PrefixSum2D(null));
+ assertThrows(IllegalArgumentException.class, () -> new PrefixSum2D(new int[][] {})); // empty
+ assertThrows(IllegalArgumentException.class, () -> new PrefixSum2D(new int[][] {{}})); // empty row
+ }
+
+ @Test
+ @DisplayName("Test invalid query ranges")
+ void testInvalidRanges() {
+ int[][] matrix = {{1, 2}, {3, 4}};
+ PrefixSum2D ps = new PrefixSum2D(matrix);
+
+ // Negative indices
+ assertThrows(IndexOutOfBoundsException.class, () -> ps.sumRegion(-1, 0, 0, 0));
+ assertThrows(IndexOutOfBoundsException.class, () -> ps.sumRegion(0, -1, 0, 0));
+
+ // Out of bounds
+ assertThrows(IndexOutOfBoundsException.class, () -> ps.sumRegion(0, 0, 2, 0)); // row2 too big
+ assertThrows(IndexOutOfBoundsException.class, () -> ps.sumRegion(0, 0, 0, 2)); // col2 too big
+
+ // Inverted ranges (start > end)
+ assertThrows(IndexOutOfBoundsException.class, () -> ps.sumRegion(1, 0, 0, 0)); // row1 > row2
+ assertThrows(IndexOutOfBoundsException.class, () -> ps.sumRegion(0, 1, 0, 0)); // col1 > col2
+ }
+}
diff --git a/src/test/java/com/thealgorithms/prefixsum/PrefixSumTest.java b/src/test/java/com/thealgorithms/prefixsum/PrefixSumTest.java
new file mode 100644
index 000000000000..a421b62e9306
--- /dev/null
+++ b/src/test/java/com/thealgorithms/prefixsum/PrefixSumTest.java
@@ -0,0 +1,80 @@
+package com.thealgorithms.prefixsum;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+
+class PrefixSumTest {
+
+ @Test
+ @DisplayName("Test basic sum with positive integers")
+ void testStandardCase() {
+ int[] input = {1, 2, 3, 4, 5};
+ PrefixSum ps = new PrefixSum(input);
+
+ // Sum of range [0, 4] -> 15
+ assertEquals(15L, ps.sumRange(0, 4));
+
+ // Sum of range [1, 3] -> 9
+ assertEquals(9L, ps.sumRange(1, 3));
+ }
+
+ @Test
+ @DisplayName("Test array with negative numbers and zeros")
+ void testNegativeAndZeros() {
+ int[] input = {-2, 0, 3, -5, 2, -1};
+ PrefixSum ps = new PrefixSum(input);
+
+ assertEquals(1L, ps.sumRange(0, 2));
+ assertEquals(-1L, ps.sumRange(2, 5));
+ assertEquals(0L, ps.sumRange(1, 1));
+ }
+
+ @Test
+ @DisplayName("Test with large integers to verify overflow handling")
+ void testLargeNumbers() {
+ // Two values that fit in int, but their sum exceeds Integer.MAX_VALUE
+ // Integer.MAX_VALUE is approx 2.14 billion.
+ int val = 2_000_000_000;
+ int[] input = {val, val, val};
+ PrefixSum ps = new PrefixSum(input);
+
+ // Sum of three 2 billion values is 6 billion (fits in long, overflows int)
+ assertEquals(6_000_000_000L, ps.sumRange(0, 2));
+ }
+
+ @Test
+ @DisplayName("Test single element array")
+ void testSingleElement() {
+ int[] input = {42};
+ PrefixSum ps = new PrefixSum(input);
+ assertEquals(42L, ps.sumRange(0, 0));
+ }
+
+ @Test
+ @DisplayName("Test constructor with null input")
+ void testNullInput() {
+ assertThrows(IllegalArgumentException.class, () -> new PrefixSum(null));
+ }
+
+ @Test
+ @DisplayName("Test empty array behavior")
+ void testEmptyArray() {
+ int[] input = {};
+ PrefixSum ps = new PrefixSum(input);
+ assertThrows(IndexOutOfBoundsException.class, () -> ps.sumRange(0, 0));
+ }
+
+ @Test
+ @DisplayName("Test invalid range indices")
+ void testInvalidIndices() {
+ int[] input = {10, 20, 30};
+ PrefixSum ps = new PrefixSum(input);
+
+ assertThrows(IndexOutOfBoundsException.class, () -> ps.sumRange(-1, 1));
+ assertThrows(IndexOutOfBoundsException.class, () -> ps.sumRange(0, 3));
+ assertThrows(IndexOutOfBoundsException.class, () -> ps.sumRange(2, 1));
+ }
+}
diff --git a/src/test/java/com/thealgorithms/prefixsum/RangeSumQueryTest.java b/src/test/java/com/thealgorithms/prefixsum/RangeSumQueryTest.java
new file mode 100644
index 000000000000..12072318ac74
--- /dev/null
+++ b/src/test/java/com/thealgorithms/prefixsum/RangeSumQueryTest.java
@@ -0,0 +1,73 @@
+package com.thealgorithms.prefixsum;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+import org.junit.jupiter.api.Test;
+
+/**
+ * Tests for {@link RangeSumQuery}.
+ */
+class RangeSumQueryTest {
+
+ @Test
+ void testBasicExample() {
+ int[] nums = {1, 2, 3, 4, 5};
+ int[] prefixSum = RangeSumQuery.buildPrefixSum(nums);
+
+ assertEquals(6, RangeSumQuery.sumRange(prefixSum, 0, 2)); // 1+2+3
+ assertEquals(9, RangeSumQuery.sumRange(prefixSum, 1, 3)); // 2+3+4
+ assertEquals(15, RangeSumQuery.sumRange(prefixSum, 0, 4)); // 1+2+3+4+5
+ assertEquals(12, RangeSumQuery.sumRange(prefixSum, 2, 4)); // 3+4+5
+ }
+
+ @Test
+ void testSingleElement() {
+ int[] nums = {7};
+ int[] prefixSum = RangeSumQuery.buildPrefixSum(nums);
+
+ assertEquals(7, RangeSumQuery.sumRange(prefixSum, 0, 0));
+ }
+
+ @Test
+ void testAllZeros() {
+ int[] nums = {0, 0, 0, 0};
+ int[] prefixSum = RangeSumQuery.buildPrefixSum(nums);
+
+ assertEquals(0, RangeSumQuery.sumRange(prefixSum, 0, 3));
+ assertEquals(0, RangeSumQuery.sumRange(prefixSum, 1, 2));
+ }
+
+ @Test
+ void testNegativeNumbers() {
+ int[] nums = {-1, 2, -3, 4};
+ int[] prefixSum = RangeSumQuery.buildPrefixSum(nums);
+
+ assertEquals(-2, RangeSumQuery.sumRange(prefixSum, 0, 2)); // -1+2-3
+ assertEquals(3, RangeSumQuery.sumRange(prefixSum, 1, 3)); // 2-3+4
+ }
+
+ @Test
+ void testEmptyArrayThrowsException() {
+ int[] nums = {};
+ int[] prefixSum = RangeSumQuery.buildPrefixSum(nums);
+
+ assertThrows(IllegalArgumentException.class, () -> RangeSumQuery.sumRange(prefixSum, 0, 0));
+ }
+
+ @Test
+ void testNullArrayThrowsException() {
+ assertThrows(IllegalArgumentException.class, () -> RangeSumQuery.buildPrefixSum(null));
+ assertThrows(IllegalArgumentException.class, () -> RangeSumQuery.sumRange(null, 0, 0));
+ }
+
+ @Test
+ void testInvalidIndicesThrowsException() {
+ int[] nums = {1, 2, 3};
+ int[] prefixSum = RangeSumQuery.buildPrefixSum(nums);
+
+ assertThrows(IllegalArgumentException.class, () -> RangeSumQuery.sumRange(prefixSum, -1, 2));
+ assertThrows(IllegalArgumentException.class, () -> RangeSumQuery.sumRange(prefixSum, 1, 5));
+ assertThrows(IllegalArgumentException.class, () -> RangeSumQuery.sumRange(prefixSum, 2, 1));
+ }
+}
diff --git a/src/test/java/com/thealgorithms/prefixsum/SubarraySumEqualskTest.java b/src/test/java/com/thealgorithms/prefixsum/SubarraySumEqualskTest.java
new file mode 100644
index 000000000000..68f85b713046
--- /dev/null
+++ b/src/test/java/com/thealgorithms/prefixsum/SubarraySumEqualskTest.java
@@ -0,0 +1,59 @@
+package com.thealgorithms.prefixsum;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+import org.junit.jupiter.api.Test;
+
+/**
+ * Tests for {@link SubarraySumEqualsK}.
+ */
+class SubarraySumEqualsKTest {
+
+ @Test
+ void testBasicExample() {
+ int[] nums = {1, 1, 1};
+ int k = 2;
+ assertEquals(2, SubarraySumEqualsK.countSubarrays(nums, k));
+ }
+
+ @Test
+ void testWithNegativeNumbers() {
+ int[] nums = {1, -1, 0};
+ int k = 0;
+ assertEquals(3, SubarraySumEqualsK.countSubarrays(nums, k));
+ }
+
+ @Test
+ void testSingleElementEqualToK() {
+ int[] nums = {5};
+ int k = 5;
+ assertEquals(1, SubarraySumEqualsK.countSubarrays(nums, k));
+ }
+
+ @Test
+ void testSingleElementNotEqualToK() {
+ int[] nums = {5};
+ int k = 3;
+ assertEquals(0, SubarraySumEqualsK.countSubarrays(nums, k));
+ }
+
+ @Test
+ void testAllZeros() {
+ int[] nums = {0, 0, 0};
+ int k = 0;
+ assertEquals(6, SubarraySumEqualsK.countSubarrays(nums, k));
+ }
+
+ @Test
+ void testEmptyArray() {
+ int[] nums = {};
+ int k = 0;
+ assertEquals(0, SubarraySumEqualsK.countSubarrays(nums, k));
+ }
+
+ @Test
+ void testNullArrayThrowsException() {
+ assertThrows(IllegalArgumentException.class, () -> SubarraySumEqualsK.countSubarrays(null, 0));
+ }
+}
diff --git a/src/test/java/com/thealgorithms/puzzlesandgames/TowerOfHanoiTest.java b/src/test/java/com/thealgorithms/puzzlesandgames/TowerOfHanoiTest.java
index 42669eb03bb4..f0a2686d3e4b 100644
--- a/src/test/java/com/thealgorithms/puzzlesandgames/TowerOfHanoiTest.java
+++ b/src/test/java/com/thealgorithms/puzzlesandgames/TowerOfHanoiTest.java
@@ -1,14 +1,31 @@
package com.thealgorithms.puzzlesandgames;
import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
import static org.junit.jupiter.api.Assertions.assertTrue;
import java.util.ArrayList;
import java.util.List;
+import java.util.stream.Stream;
import org.junit.jupiter.api.Test;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.Arguments;
+import org.junit.jupiter.params.provider.MethodSource;
public class TowerOfHanoiTest {
+ @ParameterizedTest
+ @MethodSource("diskCountAndMoveCount")
+ void testMoveCountMatchesFormula(int disks, int expectedMoves) {
+ List result = new ArrayList<>();
+ TowerOfHanoi.shift(disks, "A", "B", "C", result);
+ assertEquals(expectedMoves, result.size());
+ }
+
+ private static Stream diskCountAndMoveCount() {
+ return Stream.of(Arguments.of(1, 1), Arguments.of(2, 3), Arguments.of(3, 7), Arguments.of(4, 15), Arguments.of(5, 31), Arguments.of(10, 1023));
+ }
+
@Test
public void testHanoiWithOneDisc() {
List result = new ArrayList<>();
@@ -39,6 +56,15 @@ public void testHanoiWithThreeDiscs() {
assertEquals(expected, result);
}
+ @Test
+ public void testHanoiWithDifferentPoles() {
+ List result = new ArrayList<>();
+ TowerOfHanoi.shift(2, "X", "Y", "Z", result);
+
+ List expected = List.of("Move 1 from X to Y", "Move 2 from X to Z", "Move 1 from Y to Z");
+ assertEquals(expected, result);
+ }
+
@Test
public void testHanoiWithZeroDiscs() {
List result = new ArrayList<>();
@@ -47,4 +73,10 @@ public void testHanoiWithZeroDiscs() {
// There should be no moves if there are 0 discs
assertTrue(result.isEmpty());
}
+
+ @Test
+ public void testHanoiWithNegativeDiscsThrows() {
+ List result = new ArrayList<>();
+ assertThrows(IllegalArgumentException.class, () -> TowerOfHanoi.shift(-1, "Pole1", "Pole2", "Pole3", result));
+ }
}
diff --git a/src/test/java/com/thealgorithms/searches/BinarySearch2dArrayTest.java b/src/test/java/com/thealgorithms/searches/BinarySearch2dArrayTest.java
index 18f0afc6a0a6..dec2c86de9c7 100644
--- a/src/test/java/com/thealgorithms/searches/BinarySearch2dArrayTest.java
+++ b/src/test/java/com/thealgorithms/searches/BinarySearch2dArrayTest.java
@@ -117,7 +117,7 @@ public void binarySearch2dArrayTestTargetInMiddle() {
int target = 8;
// Assert that the requirement, that the target is in the middle row and middle column, is
// fulfilled.
- assertEquals(arr[arr.length / 2][arr[0].length / 2], target);
+ assertEquals(target, arr[arr.length / 2][arr[0].length / 2]);
int[] ans = BinarySearch2dArray.binarySearch(arr, target);
System.out.println(Arrays.toString(ans));
assertEquals(1, ans[0]);
@@ -135,8 +135,8 @@ public void binarySearch2dArrayTestTargetAboveMiddleRowInMiddleColumn() {
// Assert that the requirement, that he target is in the middle column,
// in an array with an even number of columns, and on the row "above" the middle row.
- assertEquals(arr[0].length % 2, 0);
- assertEquals(arr[arr.length / 2 - 1][arr[0].length / 2], target);
+ assertEquals(0, arr[0].length % 2);
+ assertEquals(target, arr[arr.length / 2 - 1][arr[0].length / 2]);
int[] ans = BinarySearch2dArray.binarySearch(arr, target);
System.out.println(Arrays.toString(ans));
assertEquals(0, ans[0]);
diff --git a/src/test/java/com/thealgorithms/searches/KMPSearchTest.java b/src/test/java/com/thealgorithms/searches/KMPSearchTest.java
index cb804ac6a6a3..216c5fcd7d2c 100644
--- a/src/test/java/com/thealgorithms/searches/KMPSearchTest.java
+++ b/src/test/java/com/thealgorithms/searches/KMPSearchTest.java
@@ -14,7 +14,7 @@ public void kmpSearchTestLast() {
KMPSearch kmpSearch = new KMPSearch();
int value = kmpSearch.kmpSearch(pat, txt);
System.out.println(value);
- assertEquals(value, 10);
+ assertEquals(10, value);
}
@Test
@@ -25,7 +25,7 @@ public void kmpSearchTestFront() {
KMPSearch kmpSearch = new KMPSearch();
int value = kmpSearch.kmpSearch(pat, txt);
System.out.println(value);
- assertEquals(value, 0);
+ assertEquals(0, value);
}
@Test
@@ -36,7 +36,7 @@ public void kmpSearchTestMiddle() {
KMPSearch kmpSearch = new KMPSearch();
int value = kmpSearch.kmpSearch(pat, txt);
System.out.println(value);
- assertEquals(value, 4);
+ assertEquals(4, value);
}
@Test
@@ -47,7 +47,7 @@ public void kmpSearchTestNotFound() {
KMPSearch kmpSearch = new KMPSearch();
int value = kmpSearch.kmpSearch(pat, txt);
System.out.println(value);
- assertEquals(value, 4);
+ assertEquals(4, value);
}
@Test
@@ -58,6 +58,6 @@ public void kmpSearchTest4() {
KMPSearch kmpSearch = new KMPSearch();
int value = kmpSearch.kmpSearch(pat, txt);
System.out.println(value);
- assertEquals(value, -1);
+ assertEquals(-1, value);
}
}
diff --git a/src/test/java/com/thealgorithms/searches/LinearSearchThreadTest.java b/src/test/java/com/thealgorithms/searches/LinearSearchThreadTest.java
index 534c2a4487b2..c0d82489209f 100644
--- a/src/test/java/com/thealgorithms/searches/LinearSearchThreadTest.java
+++ b/src/test/java/com/thealgorithms/searches/LinearSearchThreadTest.java
@@ -3,6 +3,7 @@
import static org.junit.jupiter.api.Assertions.assertFalse;
import static org.junit.jupiter.api.Assertions.assertTrue;
+import java.util.Random;
import org.junit.jupiter.api.Test;
class LinearSearchThreadTest {
@@ -62,10 +63,11 @@ void testSearcherEmptySegment() throws InterruptedException {
void testSearcherRandomNumbers() throws InterruptedException {
int size = 200;
int[] array = new int[size];
+ Random random = new Random();
for (int i = 0; i < size; i++) {
- array[i] = (int) (Math.random() * 100);
+ array[i] = random.nextInt(100);
}
- int target = array[(int) (Math.random() * size)]; // Randomly select a target that is present
+ final int target = array[random.nextInt(size)]; // Randomly select a target that is present
Searcher searcher = new Searcher(array, 0, size, target);
searcher.start();
searcher.join();
diff --git a/src/test/java/com/thealgorithms/searches/PerfectBinarySearchTest.java b/src/test/java/com/thealgorithms/searches/PerfectBinarySearchTest.java
deleted file mode 100644
index 6eab20f45467..000000000000
--- a/src/test/java/com/thealgorithms/searches/PerfectBinarySearchTest.java
+++ /dev/null
@@ -1,44 +0,0 @@
-package com.thealgorithms.searches;
-
-import static org.junit.jupiter.api.Assertions.assertEquals;
-
-import org.junit.jupiter.api.Test;
-
-/**
- * @author D Sunil (https://github.com/sunilnitdgp)
- * @see PerfectBinarySearch
- */
-public class PerfectBinarySearchTest {
-
- @Test
- public void testIntegerBinarySearch() {
- Integer[] array = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10};
- PerfectBinarySearch binarySearch = new PerfectBinarySearch<>();
-
- // Test cases for elements present in the array
- assertEquals(0, binarySearch.find(array, 1)); // First element
- assertEquals(4, binarySearch.find(array, 5)); // Middle element
- assertEquals(9, binarySearch.find(array, 10)); // Last element
- assertEquals(6, binarySearch.find(array, 7)); // Element in the middle
-
- // Test cases for elements not in the array
- assertEquals(-1, binarySearch.find(array, 0)); // Element before the array
- assertEquals(-1, binarySearch.find(array, 11)); // Element after the array
- assertEquals(-1, binarySearch.find(array, 100)); // Element not in the array
- }
-
- @Test
- public void testStringBinarySearch() {
- String[] array = {"apple", "banana", "cherry", "date", "fig"};
- PerfectBinarySearch binarySearch = new PerfectBinarySearch<>();
-
- // Test cases for elements not in the array
- assertEquals(-1, binarySearch.find(array, "apricot")); // Element not in the array
- assertEquals(-1, binarySearch.find(array, "bananaa")); // Element not in the array
-
- // Test cases for elements present in the array
- assertEquals(0, binarySearch.find(array, "apple")); // First element
- assertEquals(2, binarySearch.find(array, "cherry")); // Middle element
- assertEquals(4, binarySearch.find(array, "fig")); // Last element
- }
-}
diff --git a/src/test/java/com/thealgorithms/searches/QuickSelectTest.java b/src/test/java/com/thealgorithms/searches/QuickSelectTest.java
index cf160b0ff4b5..4c96be76861a 100644
--- a/src/test/java/com/thealgorithms/searches/QuickSelectTest.java
+++ b/src/test/java/com/thealgorithms/searches/QuickSelectTest.java
@@ -172,7 +172,7 @@ void quickSelect70thPercentileOfManyElements() {
void quickSelectMedianOfThreeCharacters() {
List elements = Arrays.asList('X', 'Z', 'Y');
char actual = QuickSelect.select(elements, 1);
- assertEquals(actual, 'Y');
+ assertEquals('Y', actual);
}
@Test
diff --git a/src/test/java/com/thealgorithms/searches/SortOrderAgnosticBinarySearchTest.java b/src/test/java/com/thealgorithms/searches/SortOrderAgnosticBinarySearchTest.java
deleted file mode 100644
index e2917733d1d9..000000000000
--- a/src/test/java/com/thealgorithms/searches/SortOrderAgnosticBinarySearchTest.java
+++ /dev/null
@@ -1,26 +0,0 @@
-package com.thealgorithms.searches;
-
-import static org.junit.jupiter.api.Assertions.assertEquals;
-
-import org.junit.jupiter.api.Test;
-
-public class SortOrderAgnosticBinarySearchTest {
-
- @Test
- public void testAscending() {
- int[] arr = {1, 2, 3, 4, 5}; // for ascending order.
- int target = 2;
- int ans = SortOrderAgnosticBinarySearch.find(arr, target);
- int excepted = 1;
- assertEquals(excepted, ans);
- }
-
- @Test
- public void testDescending() {
- int[] arr = {5, 4, 3, 2, 1}; // for descending order.
- int target = 2;
- int ans = SortOrderAgnosticBinarySearch.find(arr, target);
- int excepted = 3;
- assertEquals(excepted, ans);
- }
-}
diff --git a/src/test/java/com/thealgorithms/sorts/TopologicalSortTest.java b/src/test/java/com/thealgorithms/sorts/TopologicalSortTest.java
index d5588b2b968e..e19f5b928263 100644
--- a/src/test/java/com/thealgorithms/sorts/TopologicalSortTest.java
+++ b/src/test/java/com/thealgorithms/sorts/TopologicalSortTest.java
@@ -58,7 +58,7 @@ public void failureTest() {
Exception exception = assertThrows(RuntimeException.class, () -> TopologicalSort.sort(graph));
String expected = "This graph contains a cycle. No linear ordering is possible. "
+ "Back edge: 6 -> 2";
- assertEquals(exception.getMessage(), expected);
+ assertEquals(expected, exception.getMessage());
}
@Test
void testEmptyGraph() {
diff --git a/src/test/java/com/thealgorithms/strings/KMPTest.java b/src/test/java/com/thealgorithms/strings/KMPTest.java
new file mode 100644
index 000000000000..9fa5f398d420
--- /dev/null
+++ b/src/test/java/com/thealgorithms/strings/KMPTest.java
@@ -0,0 +1,29 @@
+package com.thealgorithms.strings;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import java.util.List;
+import org.junit.jupiter.api.Test;
+
+public class KMPTest {
+
+ @Test
+ public void testNullInputs() {
+ assertEquals(List.of(), KMP.kmpMatcher(null, "A"));
+ assertEquals(List.of(), KMP.kmpMatcher("A", null));
+ assertEquals(List.of(), KMP.kmpMatcher(null, null));
+ }
+
+ @Test
+ public void testKMPMatcher() {
+ assertEquals(List.of(0, 1), KMP.kmpMatcher("AAAAABAAABA", "AAAA"));
+ assertEquals(List.of(0, 3), KMP.kmpMatcher("ABCABC", "ABC"));
+ assertEquals(List.of(10), KMP.kmpMatcher("ABABDABACDABABCABAB", "ABABCABAB"));
+ assertEquals(List.of(), KMP.kmpMatcher("ABCDE", "FGH"));
+ assertEquals(List.of(), KMP.kmpMatcher("A", "AA"));
+ assertEquals(List.of(0, 1, 2), KMP.kmpMatcher("AAA", "A"));
+ assertEquals(List.of(0), KMP.kmpMatcher("A", "A"));
+ assertEquals(List.of(), KMP.kmpMatcher("", "A"));
+ assertEquals(List.of(), KMP.kmpMatcher("A", ""));
+ }
+}
diff --git a/src/test/java/com/thealgorithms/strings/KasaiAlgorithmTest.java b/src/test/java/com/thealgorithms/strings/KasaiAlgorithmTest.java
new file mode 100644
index 000000000000..c22cc77df18a
--- /dev/null
+++ b/src/test/java/com/thealgorithms/strings/KasaiAlgorithmTest.java
@@ -0,0 +1,75 @@
+package com.thealgorithms.strings;
+
+import static org.junit.jupiter.api.Assertions.assertArrayEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+import org.junit.jupiter.api.Test;
+
+public class KasaiAlgorithmTest {
+
+ @Test
+ public void testKasaiBanana() {
+ String text = "banana";
+ // Suffixes:
+ // 0: banana
+ // 1: anana
+ // 2: nana
+ // 3: ana
+ // 4: na
+ // 5: a
+ //
+ // Sorted Suffixes:
+ // 5: a
+ // 3: ana
+ // 1: anana
+ // 0: banana
+ // 4: na
+ // 2: nana
+ int[] suffixArr = {5, 3, 1, 0, 4, 2};
+
+ int[] expectedLcp = {1, 3, 0, 0, 2, 0};
+
+ assertArrayEquals(expectedLcp, KasaiAlgorithm.kasai(text, suffixArr));
+ }
+
+ @Test
+ public void testKasaiAaaa() {
+ String text = "aaaa";
+ // Sorted Suffixes:
+ // 3: a
+ // 2: aa
+ // 1: aaa
+ // 0: aaaa
+ int[] suffixArr = {3, 2, 1, 0};
+ int[] expectedLcp = {1, 2, 3, 0};
+
+ assertArrayEquals(expectedLcp, KasaiAlgorithm.kasai(text, suffixArr));
+ }
+
+ @Test
+ public void testKasaiEmptyString() {
+ assertArrayEquals(new int[0], KasaiAlgorithm.kasai("", new int[0]));
+ }
+
+ @Test
+ public void testKasaiSingleChar() {
+ assertArrayEquals(new int[] {0}, KasaiAlgorithm.kasai("A", new int[] {0}));
+ }
+
+ @Test
+ public void testKasaiNullTextOrSuffixArray() {
+ assertThrows(IllegalArgumentException.class, () -> KasaiAlgorithm.kasai(null, new int[] {0}));
+ assertThrows(IllegalArgumentException.class, () -> KasaiAlgorithm.kasai("A", null));
+ }
+
+ @Test
+ public void testKasaiInvalidSuffixArrayLength() {
+ assertThrows(IllegalArgumentException.class, () -> KasaiAlgorithm.kasai("A", new int[] {0, 1}));
+ }
+
+ @Test
+ public void testKasaiInvalidSuffixArrayIndex() {
+ assertThrows(IllegalArgumentException.class, () -> KasaiAlgorithm.kasai("A", new int[] {1})); // Out of bounds
+ assertThrows(IllegalArgumentException.class, () -> KasaiAlgorithm.kasai("A", new int[] {-1})); // Out of bounds
+ }
+}
diff --git a/src/test/java/com/thealgorithms/strings/LongestPalindromicSubstringTest.java b/src/test/java/com/thealgorithms/strings/LongestPalindromicSubstringTest.java
deleted file mode 100644
index aa13c0f4a474..000000000000
--- a/src/test/java/com/thealgorithms/strings/LongestPalindromicSubstringTest.java
+++ /dev/null
@@ -1,21 +0,0 @@
-package com.thealgorithms.strings;
-
-import static org.junit.jupiter.api.Assertions.assertEquals;
-
-import java.util.stream.Stream;
-import org.junit.jupiter.params.ParameterizedTest;
-import org.junit.jupiter.params.provider.Arguments;
-import org.junit.jupiter.params.provider.MethodSource;
-
-class LongestPalindromicSubstringTest {
-
- @ParameterizedTest
- @MethodSource("provideTestCasesForLongestPalindrome")
- void testLongestPalindrome(String input, String expected) {
- assertEquals(expected, LongestPalindromicSubstring.longestPalindrome(input));
- }
-
- private static Stream provideTestCasesForLongestPalindrome() {
- return Stream.of(Arguments.of("babad", "bab"), Arguments.of("cbbd", "bb"), Arguments.of("a", "a"), Arguments.of("", ""), Arguments.of("abc", "a"), Arguments.of(null, ""), Arguments.of("aaaaa", "aaaaa"));
- }
-}
diff --git a/src/test/java/com/thealgorithms/strings/LongestRepeatedSubstringTest.java b/src/test/java/com/thealgorithms/strings/LongestRepeatedSubstringTest.java
new file mode 100644
index 000000000000..366f6863340d
--- /dev/null
+++ b/src/test/java/com/thealgorithms/strings/LongestRepeatedSubstringTest.java
@@ -0,0 +1,33 @@
+package com.thealgorithms.strings;
+
+import static org.junit.jupiter.api.Assertions.assertArrayEquals;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import java.util.stream.Stream;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.Arguments;
+import org.junit.jupiter.params.provider.MethodSource;
+
+class LongestRepeatedSubstringTest {
+
+ @ParameterizedTest(name = "\"{0}\" -> \"{1}\"")
+ @MethodSource("provideTestCases")
+ void testLongestRepeatedSubstring(String input, String expected) {
+ assertEquals(expected, LongestRepeatedSubstring.longestRepeatedSubstring(input));
+ }
+
+ private static Stream provideTestCases() {
+ return Stream.of(Arguments.of("banana", "ana"), Arguments.of("abcabc", "abc"), Arguments.of("aaaa", "aaa"), Arguments.of("abcd", ""), Arguments.of("a", ""), Arguments.of("", ""), Arguments.of(null, ""), Arguments.of("aab", "a"), Arguments.of("aa", "a"), Arguments.of("mississippi", "issi"));
+ }
+
+ @ParameterizedTest(name = "\"{0}\" -> LCP={1}")
+ @MethodSource("provideLcpTestCases")
+ void testBuildLcpArray(String input, int[] expectedLcp) {
+ int[] suffixArray = SuffixArray.buildSuffixArray(input);
+ assertArrayEquals(expectedLcp, LongestRepeatedSubstring.buildLcpArray(input, suffixArray));
+ }
+
+ private static Stream provideLcpTestCases() {
+ return Stream.of(Arguments.of("banana", new int[] {1, 3, 0, 0, 2}), Arguments.of("ab", new int[] {0}));
+ }
+}
diff --git a/src/test/java/com/thealgorithms/strings/RabinKarpTest.java b/src/test/java/com/thealgorithms/strings/RabinKarpTest.java
new file mode 100644
index 000000000000..6dfd099e9bca
--- /dev/null
+++ b/src/test/java/com/thealgorithms/strings/RabinKarpTest.java
@@ -0,0 +1,46 @@
+package com.thealgorithms.strings;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import java.util.List;
+import org.junit.jupiter.api.Test;
+
+public class RabinKarpTest {
+
+ @Test
+ public void testNullInputs() {
+ assertEquals(List.of(), RabinKarp.search(null, "A"));
+ assertEquals(List.of(), RabinKarp.search("A", null));
+ assertEquals(List.of(), RabinKarp.search(null, null));
+ }
+
+ @Test
+ public void testHashCollision() {
+ // 'a' = 97. (char)198 % 101 = 97.
+ // For length 1, h = 1. p = 97. t = 198 % 101 = 97.
+ // Collision occurs, loop checks characters: 198 != 97, breaks.
+ char collisionChar = (char) 198;
+ String text = String.valueOf(collisionChar);
+ String pattern = "a";
+ assertEquals(List.of(), RabinKarp.search(text, pattern));
+ }
+
+ @Test
+ public void testSearchWithCustomQ() {
+ // Using a different prime
+ assertEquals(List.of(0, 1), RabinKarp.search("AAAA", "AAA", 13));
+ }
+
+ @Test
+ public void testRabinKarpSearch() {
+ assertEquals(List.of(0, 1), RabinKarp.search("AAAAABAAABA", "AAAA"));
+ assertEquals(List.of(0, 3), RabinKarp.search("ABCABC", "ABC"));
+ assertEquals(List.of(10), RabinKarp.search("ABABDABACDABABCABAB", "ABABCABAB"));
+ assertEquals(List.of(), RabinKarp.search("ABCDE", "FGH"));
+ assertEquals(List.of(), RabinKarp.search("A", "AA"));
+ assertEquals(List.of(0, 1, 2), RabinKarp.search("AAA", "A"));
+ assertEquals(List.of(0), RabinKarp.search("A", "A"));
+ assertEquals(List.of(), RabinKarp.search("", "A"));
+ assertEquals(List.of(), RabinKarp.search("A", ""));
+ }
+}
diff --git a/src/test/java/com/thealgorithms/strings/RemoveStarsTest.java b/src/test/java/com/thealgorithms/strings/RemoveStarsTest.java
new file mode 100644
index 000000000000..3beb2e83399b
--- /dev/null
+++ b/src/test/java/com/thealgorithms/strings/RemoveStarsTest.java
@@ -0,0 +1,28 @@
+package com.thealgorithms.strings;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import org.junit.jupiter.api.Test;
+
+public class RemoveStarsTest {
+
+ @Test
+ void testExampleCase() {
+ assertEquals("lecoe", RemoveStars.removeStars("leet**cod*e"));
+ }
+
+ @Test
+ void testAllStars() {
+ assertEquals("", RemoveStars.removeStars("abc***"));
+ }
+
+ @Test
+ void testNoStars() {
+ assertEquals("hello", RemoveStars.removeStars("hello"));
+ }
+
+ @Test
+ void testSingleCharacter() {
+ assertEquals("", RemoveStars.removeStars("a*"));
+ }
+}
diff --git a/src/test/java/com/thealgorithms/strings/TopKFrequentWordsTest.java b/src/test/java/com/thealgorithms/strings/TopKFrequentWordsTest.java
new file mode 100644
index 000000000000..42b2d04ff265
--- /dev/null
+++ b/src/test/java/com/thealgorithms/strings/TopKFrequentWordsTest.java
@@ -0,0 +1,34 @@
+package com.thealgorithms.strings;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+import java.util.List;
+import java.util.stream.Stream;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.Arguments;
+import org.junit.jupiter.params.provider.MethodSource;
+
+class TopKFrequentWordsTest {
+
+ @ParameterizedTest
+ @MethodSource("validTestCases")
+ void testFindTopKFrequentWords(String[] words, int k, List expected) {
+ assertEquals(expected, TopKFrequentWords.findTopKFrequentWords(words, k));
+ }
+
+ static Stream validTestCases() {
+ return Stream.of(Arguments.of(new String[] {"i", "love", "leetcode", "i", "love", "coding"}, 2, List.of("i", "love")), Arguments.of(new String[] {"the", "day", "is", "sunny", "the", "the", "the", "sunny", "is", "is"}, 4, List.of("the", "is", "sunny", "day")),
+ Arguments.of(new String[] {"bbb", "aaa", "bbb", "aaa", "ccc"}, 2, List.of("aaa", "bbb")), Arguments.of(new String[] {"one", "two", "three"}, 10, List.of("one", "three", "two")), Arguments.of(new String[] {}, 3, List.of()), Arguments.of(new String[] {"x", "x", "y"}, 0, List.of()));
+ }
+
+ @ParameterizedTest
+ @MethodSource("invalidTestCases")
+ void testFindTopKFrequentWordsInvalidInput(String[] words, int k) {
+ assertThrows(IllegalArgumentException.class, () -> TopKFrequentWords.findTopKFrequentWords(words, k));
+ }
+
+ static Stream invalidTestCases() {
+ return Stream.of(Arguments.of((String[]) null, 1), Arguments.of(new String[] {"a", null, "b"}, 2), Arguments.of(new String[] {"a"}, -1));
+ }
+}
diff --git a/src/test/java/com/thealgorithms/strings/ValidParenthesesTest.java b/src/test/java/com/thealgorithms/strings/ValidParenthesesTest.java
deleted file mode 100644
index 411b11e743b8..000000000000
--- a/src/test/java/com/thealgorithms/strings/ValidParenthesesTest.java
+++ /dev/null
@@ -1,33 +0,0 @@
-package com.thealgorithms.strings;
-
-import static org.junit.jupiter.api.Assertions.assertEquals;
-import static org.junit.jupiter.api.Assertions.assertThrows;
-import static org.junit.jupiter.api.Assertions.assertTrue;
-
-import org.junit.jupiter.api.Test;
-import org.junit.jupiter.params.ParameterizedTest;
-import org.junit.jupiter.params.provider.CsvSource;
-
-public class ValidParenthesesTest {
-
- @ParameterizedTest(name = "Input: \"{0}\" β Expected: {1}")
- @CsvSource({"'()', true", "'()[]{}', true", "'(]', false", "'{[]}', true", "'([{}])', true", "'([)]', false", "'', true", "'(', false", "')', false", "'{{{{}}}}', true", "'[({})]', true", "'[(])', false", "'[', false", "']', false", "'()()()()', true", "'(()', false", "'())', false",
- "'{[()()]()}', true"})
- void
- testIsValid(String input, boolean expected) {
- assertEquals(expected, ValidParentheses.isValid(input));
- }
-
- @Test
- void testNullInputThrows() {
- IllegalArgumentException ex = assertThrows(IllegalArgumentException.class, () -> ValidParentheses.isValid(null));
- assertEquals("Input string cannot be null", ex.getMessage());
- }
-
- @ParameterizedTest(name = "Input: \"{0}\" β throws IllegalArgumentException")
- @CsvSource({"'a'", "'()a'", "'[123]'", "'{hello}'", "'( )'", "'\t'", "'\n'", "'@#$%'"})
- void testInvalidCharactersThrow(String input) {
- IllegalArgumentException ex = assertThrows(IllegalArgumentException.class, () -> ValidParentheses.isValid(input));
- assertTrue(ex.getMessage().startsWith("Unexpected character"));
- }
-}
diff --git a/src/test/java/com/thealgorithms/strings/WordLadderTest.java b/src/test/java/com/thealgorithms/strings/WordLadderTest.java
index 221953411da7..c029940abfb0 100644
--- a/src/test/java/com/thealgorithms/strings/WordLadderTest.java
+++ b/src/test/java/com/thealgorithms/strings/WordLadderTest.java
@@ -24,7 +24,7 @@ public class WordLadderTest {
public void testWordLadder() {
List wordList1 = Arrays.asList("hot", "dot", "dog", "lot", "log", "cog");
- assertEquals(WordLadder.ladderLength("hit", "cog", wordList1), 5);
+ assertEquals(5, WordLadder.ladderLength("hit", "cog", wordList1));
}
/**
@@ -39,7 +39,7 @@ public void testWordLadder() {
public void testWordLadder2() {
List wordList2 = Arrays.asList("hot", "dot", "dog", "lot", "log");
- assertEquals(WordLadder.ladderLength("hit", "cog", wordList2), 0);
+ assertEquals(0, WordLadder.ladderLength("hit", "cog", wordList2));
}
/**
@@ -54,7 +54,7 @@ public void testWordLadder2() {
public void testWordLadder3() {
List wordList3 = emptyList();
- assertEquals(WordLadder.ladderLength("hit", "cog", wordList3), 0);
+ assertEquals(0, WordLadder.ladderLength("hit", "cog", wordList3));
}
@ParameterizedTest
diff --git a/src/test/java/com/thealgorithms/strings/zigZagPattern/ZigZagPatternTest.java b/src/test/java/com/thealgorithms/strings/zigZagPattern/ZigZagPatternTest.java
index 2cbbfe3d2dd8..9bf118c9b844 100644
--- a/src/test/java/com/thealgorithms/strings/zigZagPattern/ZigZagPatternTest.java
+++ b/src/test/java/com/thealgorithms/strings/zigZagPattern/ZigZagPatternTest.java
@@ -9,8 +9,8 @@ public class ZigZagPatternTest {
public void testZigZagPattern() {
String input1 = "HelloWorldFromJava";
String input2 = "javaIsAProgrammingLanguage";
- Assertions.assertEquals(ZigZagPattern.encode(input1, 4), "HooeWrrmalolFJvlda");
- Assertions.assertEquals(ZigZagPattern.encode(input2, 4), "jAaLgasPrmgaaevIrgmnnuaoig");
+ Assertions.assertEquals("HooeWrrmalolFJvlda", ZigZagPattern.encode(input1, 4));
+ Assertions.assertEquals("jAaLgasPrmgaaevIrgmnnuaoig", ZigZagPattern.encode(input2, 4));
// Edge cases
Assertions.assertEquals("ABC", ZigZagPattern.encode("ABC", 1)); // Single row
Assertions.assertEquals("A", ZigZagPattern.encode("A", 2)); // numRows > length of string