Day 22: use tuples instead of lists, allow usage of sets in tests

Author: thatguyintech

day22/permutations.py

@@ -2,18 +2,19 @@ def permutations(arr):
     allPermutations = list()
 
     if len(arr) < 1:
-        return [[]]
+        return [()]
     else:
         for i in xrange(len(arr)):
             for permutation in permutations(arr[1:]):
-                allPermutations.append(permutation[:i] + arr[0:1] + permutation[i:])
+                allPermutations.append(permutation[:i] + (arr[0],) + permutation[i:])
 
     return allPermutations
 
 def main():
-    assert permutations([1]) == [[1]]
-    assert permutations([1,2]) == [[1, 2], [2, 1]]
-    assert permutations([1,2,3]) == [[1, 2, 3], [1, 3, 2], [2, 1, 3], [3, 1, 2], [2, 3, 1], [3, 2, 1]]
+    assert set(permutations([])) == set([()])
+    assert set(permutations([1])) == set([(1,)])
+    assert set(permutations([1,2])) == set([(1, 2), (2, 1)])
+    assert set(permutations([1,2,3])) == set([(1, 2, 3), (1, 3, 2), (2, 1, 3), (3, 1, 2), (2, 3, 1), (3, 2, 1)])
 
 if __name__ == "__main__":
     main()