leetcode77.组合
其实就是全排列问题
class Solution { public: int nn,kk; vector<vector<int>> res; vector<int>t; int num=0; void dfs(){ if(num==kk){ res.push_back(t); return; } int i; for(i=t[num-1]+1;i<=nn;i++){ t.push_back(i); num++; dfs(); num--; t.pop_back(); } } vector<vector<int>> combine(int n, int k) { nn=n; kk=k; int i; for(i=1;i<=n;i++){ t.push_back(i); num++; dfs(); num--; t.pop_back(); } return res; } };