Merge sort

Author: ryanmcdermott

merge_sort/merge_sort.py

@@ -0,0 +1,35 @@
+def merge_sort(arr):
+    if len(arr) <= 1:
+        return arr
+
+    i = 0
+    j = 0
+    k = 0
+
+    mid = len(arr) // 2
+    left = arr[:mid]
+    right = arr[mid:]
+
+    merge_sort(left)
+    merge_sort(right)
+
+    while i < len(left) and j < len(right):
+        if left[i] <= right[j]:
+            arr[k] = left[i]
+            i += 1
+        else:
+            arr[k] = right[j]
+            j += 1
+        k += 1
+
+    while i < len(left):
+        arr[k] = left[i]
+        i += 1
+        k += 1
+
+    while j < len(right):
+        arr[k] = right[j]
+        j += 1
+        k += 1
+
+    return arr

merge_sort/test_merge_sort.py

@@ -0,0 +1,29 @@
+import unittest
+from random import randrange
+from merge_sort import merge_sort as alg_sort
+
+
+class MergeSortTyes(unittest.TestCase):
+    def test_arr_positives(self):
+        arr = [randrange(0, 20) for i in range(0, 20)]
+        expected = sorted(arr)
+        actual = alg_sort(arr)
+        assert actual == expected
+
+    def test_empty_arr(self):
+        arr = []
+        expected = sorted(arr)
+        actual = alg_sort(arr)
+        assert actual == expected
+
+    def test_single_item_arr(self):
+        arr = [4]
+        expected = sorted(arr)
+        actual = alg_sort(arr)
+        assert actual == expected
+
+    def test_arr_positives_negatives(self):
+        arr = [randrange(-20, 20) for i in range(0, 20)]
+        expected = sorted(arr)
+        actual = alg_sort(arr)
+        assert actual == expected