https://leetcode.com/problems/combinations/

沿用78题的思路

class Solution {public:    void backTrack(vector
     
       ans, vector
      
        nums, vector
       
        
         >& res, int times,int k)    {        if(ans.size() == k)        {            res.push_back(ans);        }        else        {            for(int i = times; i
         

> combine(int n, int k) { vector

> res; vector

ans; vector

nums; for(int i=1;i<=n;i++) nums.push_back(i); int bgi = 0; backTrack(ans,nums,res,bgi,k); return res; }};