solution.py

from typing import List


class Solution:
    def permute(self, nums: List[int]) -> List[List[int]]:
        result = []

        if (len(nums) == 1):
            return [nums[:]]

        for i in range(len(nums)):
            n = nums.pop(0)
            perms = self.permute(nums)
            for perm in perms:
                perm.append(n)
            result.extend(perms)
            nums.append(n)
        return result


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