Uploading new problem

Microsoft_Problems/Microsoft_Problem_09.py

@@ -0,0 +1,26 @@
+"""
+This problem was asked by Microsoft.
+
+Given a number in the form of a list of digits, return all possible permutations.
+
+For example, given [1,2,3], return [[1,2,3],[1,3,2],[2,1,3],[2,3,1],[3,1,2],[3,2,1]].
+"""
+
+
+def get_permutations(arr):
+    if len(arr) < 2:
+        return [arr]
+
+    permutations = list()
+    for i, num in enumerate(arr):
+        arr_cp = arr[:i] + arr[i + 1:]
+        child_perms = get_permutations(arr_cp)
+        for perm in child_perms:
+            permutations.append([num] + perm)
+
+    return permutations
+
+
+assert get_permutations([1, 2, 3]) == \
+       [[1, 2, 3], [1, 3, 2], [2, 1, 3],
+        [2, 3, 1], [3, 1, 2], [3, 2, 1]]