46 Permutations(全排列Medium)

题目意思：全排列

思路：其实看这题目意思，是不太希望用递归的，不过还是用了递归，非递归的以后再搞吧

　　ps:vector这玩意不能随便返回，开始递归方法用vector，直接到500ms，换成void，到12ms

 1 class Solution {
 2 public:
 3     vector<vector<int>> permute(vector<int>& nums) {
 4         vector<vector<int> >ans;
 5         permute1(ans,nums,0);
 6         return ans;
 7     }
 8     void permute1(vector<vector<int>>& ans,vector<int>& nums,int begin) {
 9         if(begin==nums.size()-1){
10             ans.push_back(nums);
11         }
12         for(int i=begin;i<nums.size();++i){
13             swap(nums[i],nums[begin]);
14             permute1(ans,nums,begin+1);
15             swap(nums[i],nums[begin]);
16         }
17     }
18 };

时间： 2024-08-07 17:01:35

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