From 3d2953b72c964a0d2fd282ce7c88e2bc6608fa8f Mon Sep 17 00:00:00 2001
From: anshray <rayanshu@gmail.com>
Date: Tue, 10 Oct 2017 15:20:42 +0530
Subject: [PATCH] added timsort (untested)

---
 pygorithm/sorting/timsort.py | 98 ++++++++++++++++++++++++++++++++++++
 1 file changed, 98 insertions(+)
 create mode 100644 pygorithm/sorting/timsort.py

diff --git a/pygorithm/sorting/timsort.py b/pygorithm/sorting/timsort.py
new file mode 100644
index 0000000..cbec73b
--- /dev/null
+++ b/pygorithm/sorting/timsort.py
@@ -0,0 +1,98 @@
+#!/usr/lib/python
+# -*- coding: utf-8 -*-
+#
+#       This is a re-implementation of Python's timsort in Python
+#       itself. This is purely for learning purposes. :)
+#       References: [
+#           https://en.wikipedia.org/wiki/Timsort,
+#           http://wiki.c2.com/?TimSort
+#       ]
+#
+# Copyright 2017 Nandaja Varma <nandajavarma@gmail.com>
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Library General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+# 02110-1301,
+# USA.
+
+
+def binary_search(the_array, item, start, end):
+    if start == end:
+        if the_array[start] > item:
+            return start
+        else:
+            return start + 1
+    if start > end:
+        return start
+
+    mid = (start + end)/ 2
+    if the_array[mid] < item:
+        return binary_search(the_array, item, mid + 1, end)
+    elif the_array[mid] > item:
+        return binary_search(the_array, item, start, mid - 1)
+    else:
+        return mid
+
+
+"""
+Insertion sort that the heap sort uses if the array size is small or if
+the size of the "run" is small
+"""
+def insertion_sort(the_array):
+    l = len(the_array)
+    for index in range(1, l):
+        value = the_array[index]
+        pos = binary_search(the_array, value, 0, index - 1)
+        the_array = the_array[:pos] + [value] + the_array[pos:index] + the_array[index+1:]
+    return the_array
+
+def merge(left, right):
+    """Takes two sorted lists and returns a single sorted list by comparing the
+    elements one at a time.
+
+    [1, 2, 3, 4, 5, 6]
+    """
+    if not left:
+        return right
+    if not right:
+        return left
+    if left[0] < right[0]:
+        return [left[0]] + merge(left[1:], right)
+    return [right[0]] + merge(left, right[1:])
+
+
+def timsort(the_array):
+    runs, sorted_runs = [], []
+    l = len(the_array)
+    new_run = [the_array[0]]
+    for i in range(1, l):
+        if i == l-1:
+            new_run.append(the_array[i])
+            runs.append(new_run)
+            break
+        if the_array[i] < the_array[i-1]:
+            if not new_run:
+                runs.append([the_array[i-1]])
+                new_run.append(the_array[i])
+            else:
+                runs.append(new_run)
+                new_run = []
+        else:
+            new_run.append(the_array[i])
+    for each in runs:
+        sorted_runs.append(insertion_sort(each))
+    sorted_array = []
+    for run in sorted_runs:
+        sorted_array = merge(sorted_array, run)
+    print sorted_array