動機

經典排序列舉

Problem

Given an array nums of distinct integers, return all the possible permutations. You can return the answer in any order.

 

Example 1:

Input: nums = [1,2,3]Output: [[1,2,3],[1,3,2],[2,1,3],[2,3,1],[3,1,2],[3,2,1]]

Example 2:

Input: nums = [0,1]Output: [[0,1],[1,0]]

Example 3:

Input: nums = [1]Output: [[1]]

 

Constraints:

  • 1 <= nums.length <= 6
  • -10 <= nums[i] <= 10
  • All the integers of nums are unique.

Sol

class Solution:
    def permute(self, nums: List[int], acc = []) -> List[List[int]]:
        if not nums:
            return [acc]
        else:
            return sum([self.permute(nums[:k]+nums[k+1:], acc+[nums[k]]) for k in range(len(nums))],[])