LeetCode Combinations

// LeetCode_Combinations.cpp : 定义控制台应用程序的入口点。//#include "stdafx.h"#include <iostream>#include <vector>using namespace std;void combine_recursive(int n,int k,int i,vector<int>& res,vector<vector<int> >&ret){if(k==0){ret.push_back(res);//res.clear();return;}if(i+k>n+1)return;res.push_back(i);combine_recursive(n,k-1,i+1,res,ret);res.pop_back();combine_recursive(n,k,i+1,res,ret);}vector<vector<int> > combine(int n, int k) {vector<vector<int> >ret;if(n==0||k==0)return ret;vector<int> temp;combine_recursive(n,k,1,temp,ret);return ret;}int _tmain(int argc, _TCHAR* argv[]){vector<vector<int> >ret;ret = combine(5,3);vector<vector<int> >::iterator iter1=ret.begin();vector<int>::iterator iter2;while(iter1!=ret.end()){iter2 = iter1->begin();while(iter2!=iter1->end()){cout<<*iter2<<" ";iter2++;}cout<<endl;iter1++;}system("pause");return 0;}

剑指offer上也有，组合问题