Add comb sort algorithm

Author: kelvins

sorts/comb_sort.py

@@ -0,0 +1,58 @@
+"""
+Comb sort is a relatively simple sorting algorithm originally designed by Wlodzimierz Dobosiewicz in 1980.
+Later it was rediscovered by Stephen Lacey and Richard Box in 1991. Comb sort improves on bubble sort.
+
+This is pure python implementation of counting sort algorithm
+For doctests run following command:
+python -m doctest -v comb_sort.py
+or
+python3 -m doctest -v comb_sort.py
+
+For manual testing run:
+python comb_sort.py
+"""
+
+def comb_sort(data):
+    """Pure implementation of comb sort algorithm in Python
+    :param collection: some mutable ordered collection with heterogeneous
+    comparable items inside
+    :return: the same collection ordered by ascending
+    Examples:
+    >>> comb_sort([0, 5, 3, 2, 2])
+    [0, 2, 2, 3, 5]
+    >>> comb_sort([])
+    []
+    >>> comb_sort([-2, -5, -45])
+    [-45, -5, -2]
+    """
+    shrink_factor = 1.3
+    gap = len(data)
+    swapped = True
+    i = 0
+
+    while gap > 1 or swapped:
+    	# Update the gap value for a next comb
+        gap = int(float(gap) / shrink_factor)
+
+        swapped = False
+        i = 0
+
+        while gap + i < len(data):
+            if data[i] > data[i+gap]:
+            	# Swap values
+                data[i], data[i+gap] = data[i+gap], data[i]
+                swapped = True
+            i += 1
+
+    return data
+
+
+if __name__ == '__main__':
+    try:
+        raw_input          # Python 2
+    except NameError:
+        raw_input = input  # Python 3
+
+    user_input = raw_input('Enter numbers separated by a comma:\n').strip()
+    unsorted = [int(item) for item in user_input.split(',')]
+    print(comb_sort(unsorted))