Change the dir structure slightly

interview_problems/merge_sort.py

@@ -0,0 +1,47 @@
+#!/usr/bin/env python
+# AKA: do you believe in magic?
+
+__author__ = "bt3"
+
+def merge_sort(array):
+    if len(array) < 2:
+        return array
+    
+    # divide
+    mid = len(array)//2
+    left = merge_sort(array[:mid])
+    right = merge_sort(array[mid:])
+    
+    # merge
+    result = []
+    i, j = 0, 0
+    
+    while i < len(left) and j < len(right):
+        if left[i] < right[j]:
+            result.append(left[i])
+            i += 1
+        else:
+            result.append(right[j])
+            j+= 1
+    
+    # make sure nothing is left behind
+    if left[i:]:
+        result.extend(left[i:])
+    if right[j:]:
+        result.extend(right[j:])
+    
+    return result
+    
+    
+    
+    
+if __name__ == '__main__':
+    array = [3, 1, 6, 0, 7, 19, 7, 2, 22]
+    sorted = [0, 1, 2, 3, 6, 7, 7, 19, 22]
+    assert(merge_sort(array) == sorted)
+    
+    array = []
+    assert(merge_sort(array) == array)
+
+    array = [1]
+    assert(merge_sort(array) == array)