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codes/python/chapter_backtracking/permutations_i.py
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Yudong Jin
Some improvements (#1073)
07 фев 2024, 17:21
Не верифицирован
07 фев 2024, 17:21
a005c6e
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""" File: permutations_i.py Created Time: 2023-04-15 Author: krahets (krahets@163.com) """ def backtrack( state: list[int], choices: list[int], selected: list[bool], res: list[list[int]] ): """回溯算法：全排列 I""" # 当状态长度等于元素数量时，记录解 if len(state) == len(choices): res.append(list(state)) return # 遍历所有选择 for i, choice in enumerate(choices): # 剪枝：不允许重复选择元素 if not selected[i]: # 尝试：做出选择，更新状态 selected[i] = True state.append(choice) # 进行下一轮选择 backtrack(state, choices, selected, res) # 回退：撤销选择，恢复到之前的状态 selected[i] = False state.pop() def permutations_i(nums: list[int]) -> list[list[int]]: """全排列 I""" res = [] backtrack(state=[], choices=nums, selected=[False] * len(nums), res=res) return res """Driver Code""" if __name__ == "__main__": nums = [1, 2, 3] res = permutations_i(nums) print(f"输入数组 nums = {nums}") print(f"所有排列 res = {res}")