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data_structures/arrays/permutations.py
48 строк
1 KB
aryan1165
Fixed permute_recursive() by passing nums.copy(). Fixes #9014 (#9161)
01 окт 2023, 07:06
Не верифицирован
01 окт 2023, 07:06
320d895
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def permute_recursive(nums: list[int]) -> list[list[int]]: """ Return all permutations. >>> permute_recursive([1, 2, 3]) [[3, 2, 1], [2, 3, 1], [1, 3, 2], [3, 1, 2], [2, 1, 3], [1, 2, 3]] """ result: list[list[int]] = [] if len(nums) == 0: return [[]] for _ in range(len(nums)): n = nums.pop(0) permutations = permute_recursive(nums.copy()) for perm in permutations: perm.append(n) result.extend(permutations) nums.append(n) return result def permute_backtrack(nums: list[int]) -> list[list[int]]: """ Return all permutations of the given list. >>> permute_backtrack([1, 2, 3]) [[1, 2, 3], [1, 3, 2], [2, 1, 3], [2, 3, 1], [3, 2, 1], [3, 1, 2]] """ def backtrack(start: int) -> None: if start == len(nums) - 1: output.append(nums[:]) else: for i in range(start, len(nums)): nums[start], nums[i] = nums[i], nums[start] backtrack(start + 1) nums[start], nums[i] = nums[i], nums[start] # backtrack output: list[list[int]] = [] backtrack(0) return output if __name__ == "__main__": import doctest result = permute_backtrack([1, 2, 3]) print(result) doctest.testmod()