Added Dequeue in Python

sorts/insertion_sort.py

@@ -0,0 +1,53 @@
+"""
+This is a pure python implementation of the insertion sort algorithm
+
+For doctests run following command:
+python -m doctest -v insertion_sort.py
+or
+python3 -m doctest -v insertion_sort.py
+
+For manual testing run:
+python insertion_sort.py
+"""
+from __future__ import print_function
+
+
+def insertion_sort(collection):
+    """Pure implementation of the insertion sort algorithm in Python
+
+    :param collection: some mutable ordered collection with heterogeneous
+    comparable items inside
+    :return: the same collection ordered by ascending
+
+    Examples:
+    >>> insertion_sort([0, 5, 3, 2, 2])
+    [0, 2, 2, 3, 5]
+
+    >>> insertion_sort([])
+    []
+
+    >>> insertion_sort([-2, -5, -45])
+    [-45, -5, -2]
+    """
+    for index in range(1, len(collection)):
+        while 0 < index and collection[index] < collection[index - 1]:
+            collection[index], collection[
+                index - 1] = collection[index - 1], collection[index]
+            index -= 1
+
+    return collection
+
+
+if __name__ == '__main__':
+    import sys
+
+    # For python 2.x and 3.x compatibility: 3.x has no raw_input builtin
+    # otherwise 2.x's input builtin function is too "smart"
+    if sys.version_info.major < 3:
+        input_function = raw_input
+    else:
+        input_function = input
+
+    user_input = input_function('Enter numbers separated by a comma:\n')
+    unsorted = [int(item) for item in user_input.split(',')]
+    print(insertion_sort(unsorted))