Test cases for all_permutations

backtracking/all_permutations.py

@@ -7,16 +7,52 @@
 """
 from __future__ import annotations
 
+from itertools import permutations
 
-def generate_all_permutations(sequence: list[int | str]) -> None:
-    create_state_space_tree(sequence, [], 0, [0 for i in range(len(sequence))])
+
+def permutation_tuple_to_list(arr: list[int | str]) -> list[list[int | str]]:
+    """
+    Default permutation output is list of tuples
+    >>> permutation_tuple_to_list([1,2])
+    [[1, 2], [2, 1]]
+    >>> permutation_tuple_to_list(['a', 'b'])
+    [['a', 'b'], ['b', 'a']]
+    """
+    return [list(output_tuple) for output_tuple in permutations(arr)]
+
+
+def generate_all_permutations(sequence: list[int | str]) -> list[list[int | str]]:
+    """
+    >>> generate_all_permutations([])
+    [[]]
+    >>> generate_all_permutations([1])
+    [[1]]
+    >>> generate_all_permutations([1, 2])
+    [[1, 2], [2, 1]]
+    >>> generate_all_permutations([1, 2, 3])
+    [[1, 2, 3], [1, 3, 2], [2, 1, 3], [2, 3, 1], [3, 1, 2], [3, 2, 1]]
+    >>> generate_all_permutations([-1, 2])
+    [[-1, 2], [2, -1]]
+    >>> generate_all_permutations([1, -2])
+    [[1, -2], [-2, 1]]
+    >>> generate_all_permutations(['a', 'b'])
+    [['a', 'b'], ['b', 'a']]
+    >>> from itertools import permutations
+    >>> test_arr = [num for num in range(0, 6)]
+    >>> generate_all_permutations(test_arr) == permutation_tuple_to_list(test_arr)
+    True
+    """
+    output: list[list[int | str]] = []
+    create_state_space_tree(sequence, [], 0, [0 for i in range(len(sequence))], output)
+    return output
 
 
 def create_state_space_tree(
     sequence: list[int | str],
     current_sequence: list[int | str],
     index: int,
     index_used: list[int],
+    output: list[list[int | str]],
 ) -> None:
     """
     Creates a state space tree to iterate through each branch using DFS.
@@ -25,14 +61,20 @@ def create_state_space_tree(
     """
 
     if index == len(sequence):
-        print(current_sequence)
+        # Copying b/c popping current_sequence is part of this recursive algo.
+        # Can't have pointer to that arr
+        current_sequence_copy = list(current_sequence)
+        output.append(current_sequence_copy)
         return
 
     for i in range(len(sequence)):
         if not index_used[i]:
             current_sequence.append(sequence[i])
             index_used[i] = True
-            create_state_space_tree(sequence, current_sequence, index + 1, index_used)
+            # function spaced like this b/c linter 88 char limit
+            create_state_space_tree(
+                sequence, current_sequence, index + 1, index_used, output
+            )
             current_sequence.pop()
             index_used[i] = False
 
@@ -49,3 +91,8 @@ def create_state_space_tree(
 
 sequence_2: list[int | str] = ["A", "B", "C"]
 generate_all_permutations(sequence_2)
+
+if __name__ == "__main__":
+    from doctest import testmod
+
+    testmod()