so easy

interview_cake/math/in_place_shuffle.py

@@ -0,0 +1,33 @@
+#!/bin/python
+
+"""
+Write a function for doing an in-place shuffle of a list.
+
+The shuffle must be "uniform," meaning each item in the original list must have the same probability of ending up in each spot in the final list.
+
+Assume that you have a function get_random(floor, ceiling) for getting a random integer that is >= floor and <= ceiling.
+"""
+
+import random
+
+def get_random(floor, ceiling):
+    return random.randrange(floor, ceiling + 1)
+
+def shuffle(the_list):
+
+    if len(the_list) <= 1:
+        return the_list
+
+    last_index_in_the_list = len(the_list) - 1
+
+    for i in range(len(the_list) - 1):
+        random_choice_index = get_random(i,
+                                         last_index_in_the_list)
+        if random_choice_index != i:
+            the_list[i], the_list[random_choice_index] = \
+                the_list[random_choice_index], the_list[i]
+
+
+seed_list = [5, 2, 6, 2, 6]
+shuffle(seed_list)
+print seed_list