【leetcode】Combinations

 1 class Solution {
 2 public:
 3     static void dfs(int n,int k,int start,int cur,vector<int> &path,vector<vector<int> >&result)
 4     {
 5         if(cur==k)
 6             result.push_back(path);
 7 
 8         for(int i=start;i<=n;i++)
 9         {
10             path.push_back(i);
11             dfs(n,k,i+1,cur+1,path,result);
12             path.pop_back();
13         }
14     }
15     vector<vector<int> > combine(int n, int k) {
16         vector<vector<int> >result;
17         vector<int> path;
18         dfs(n,k,1,0,path,result);
19         return result;
20     }
21 };