Difficulty: Easy
Roman numerals are represented by seven different symbols: I, V, X, L, C, D and M.
Symbol Value
I 1
V 5
X 10
L 50
C 100
D 500
M 1000```
For example, two is written as `II` in Roman numeral, just two one's added together. Twelve is written as, `XII`, which is simply `X` + `II`. The number twenty seven is written as `XXVII`, which is `XX` + `V` + `II`.
Roman numerals are usually written largest to smallest from left to right. However, the numeral for four is not `IIII`. Instead, the number four is written as `IV`. Because the one is before the five we subtract it making four. The same principle applies to the number nine, which is written as `IX`. There are six instances where subtraction is used:
* `I` can be placed before `V` (5) and `X` (10) to make 4 and 9.
* `X` can be placed before `L` (50) and `C` (100) to make 40 and 90.
* `C` can be placed before `D` (500) and `M` (1000) to make 400 and 900.
Given a roman numeral, convert it to an integer. Input is guaranteed to be within the range from 1 to 3999.
**Example 1:**
Input: "III" Output: 3```
Example 2:
Input: "IV"
Output: 4```
**Example 3:**
Input: "IX" Output: 9```
Example 4:
Input: "LVIII"
Output: 58
Explanation: L = 50, V= 5, III = 3.
Example 5:
Input: "MCMXCIV"
Output: 1994
Explanation: M = 1000, CM = 900, XC = 90 and IV = 4.```
#### Solution
Language: **Java**
```java
class Solution {
public int romanToInt(String s) {
int result = 0;
List<String> M = Arrays.asList("MMM", "MM", "M");
List<String> C = Arrays.asList("CM", "DCCC", "DCC", "DC", "D", "CD", "CCC", "CC", "C");
List<String> X = Arrays.asList("XC", "LXXX", "LXX", "LX", "L", "XL", "XXX", "XX", "X");
List<String> I = Arrays.asList("IX", "VIII", "VII", "VI", "V", "IV", "III", "II", "I");
List<List<String>> list = Arrays.asList(M, C, X, I);
int size = 1000;
for (List<String> item : list) {
for (int i = 0; i < item.size(); i++) {
if (s.startsWith(item.get(i))) {
result += (item.size() - i) * size;
s = s.substring(item.get(i).length());
}
}
size /= 10;
}
return result;
}
}
case 'I':