46. 全排列

class Solution:
    def permute(self, nums: List[int]) -> List[List[int]]:
        
        resultList = []
        def backTrach(nums, tmp):
            if not nums:
                resultList.append(tmp)
                return 0
            for i in range(len(nums)):
                backTrach(nums[:i]+nums[i+1:], tmp+[nums[i]])
        
        backTrach(nums, [])
        return resultList