From 235ea749aa04c81852eeeba9a8e0d9f18aa0a8d3 Mon Sep 17 00:00:00 2001 From: judetommy60-ops Date: Sun, 4 Oct 2026 11:21:42 -0400 Subject: [PATCH 1/3] Add failing test for empty input in permute_backtrack --- data_structures/arrays/permutations.py | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/data_structures/arrays/permutations.py b/data_structures/arrays/permutations.py index 4906dd5c2ae1..5e112dc8074b 100644 --- a/data_structures/arrays/permutations.py +++ b/data_structures/arrays/permutations.py @@ -24,6 +24,8 @@ def permute_backtrack(nums: list[int]) -> list[list[int]]: >>> permute_backtrack([1, 2, 3]) [[1, 2, 3], [1, 3, 2], [2, 1, 3], [2, 3, 1], [3, 2, 1], [3, 1, 2]] + >>> permute_backtrack([]) + [[]] """ def backtrack(start: int) -> None: @@ -46,3 +48,7 @@ def backtrack(start: int) -> None: result = permute_backtrack([1, 2, 3]) print(result) doctest.testmod() + + + + From 267fe51f05c76470285c644eb4d73b93445c2abd Mon Sep 17 00:00:00 2001 From: judetommy60-ops Date: Wed, 21 Oct 2026 10:24:38 -0400 Subject: [PATCH 2/3] Fix empty-input handling in permute_backtrack --- data_structures/arrays/permutations.py | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/data_structures/arrays/permutations.py b/data_structures/arrays/permutations.py index 5e112dc8074b..b455cef6d902 100644 --- a/data_structures/arrays/permutations.py +++ b/data_structures/arrays/permutations.py @@ -29,7 +29,7 @@ def permute_backtrack(nums: list[int]) -> list[list[int]]: """ def backtrack(start: int) -> None: - if start == len(nums) - 1: + if start == len(nums) - 1 or len(nums) == 0: output.append(nums[:]) else: for i in range(start, len(nums)): From dcc930611cc84fcd29fe72db0e8040a00603513f Mon Sep 17 00:00:00 2001 From: "pre-commit-ci[bot]" <66853113+pre-commit-ci[bot]@users.noreply.github.com> Date: Wed, 21 Oct 2026 15:00:18 +0000 Subject: [PATCH 3/3] [pre-commit.ci] auto fixes from pre-commit.com hooks for more information, see https://pre-commit.ci --- data_structures/arrays/permutations.py | 4 ---- 1 file changed, 4 deletions(-) diff --git a/data_structures/arrays/permutations.py b/data_structures/arrays/permutations.py index b455cef6d902..3c47e8fbe713 100644 --- a/data_structures/arrays/permutations.py +++ b/data_structures/arrays/permutations.py @@ -48,7 +48,3 @@ def backtrack(start: int) -> None: result = permute_backtrack([1, 2, 3]) print(result) doctest.testmod() - - - -