from typing import List
class Solution:
    def permute(self, nums: List[int]) -> List[List[int]]:


        def dfs(nums, size, depth, path, used, res):
            if depth == size:
                res.append(path[:])

                return

            for i in range(size):
                # used[i] 为 false时
                if not used[i]:
                    used[i] = True
                    path.append(nums[i])

                    def dfs(nums, size, depth, path, used, res):
                        if depth == size:
                            res.append(path[:])

                            return

                        for i in range(size):
                            # used[i] 为 false时
                            if not used[i]:
                                used[i] = True
                                path.append(nums[i])

                                dfs(nums, size, depth + 1, path, used, res)

                                used[i] = False
                                path.pop()

                    used[i] = False
                    path.pop()

        size = len(nums)
        if len(nums) == 0:
            return []

        # 一维数组赋值
        used = [False for _ in range(size)]
        # 二维数组赋值
        # [[False for _ in range(size)] for _ in range(size)]
        res = []
        dfs(nums, size, 0, [], used, res)


        return res


if __name__ == '__main__':
    nums = [1, 2, 3]
    solution = Solution()
    res = solution.permute(nums)
    print(res)