hdu（1515）

题目：http://acm.hdu.edu.cn/showproblem.php?pid=1515

#include <stdio.h>#include<iostream>#include <stack>#include <vector>#include <string>using namespace std;string a,b;int len;stack<char>build;vector<char>oper;void dfs(int push,int pop){    if(push == len && pop==len){       for(inti = 0;i <oper.size();i++)          cout<< oper[i]<< "";       cout<< endl;    }    if(push < len){       build.push(a[push]);       oper.push_back('i');       dfs(push+1,pop);       build.pop();       oper.pop_back();    }    if(pop < push&& pop <len&& b[pop]== build.top()){       char temp =build.top();       build.pop();       oper.push_back('o');       dfs(push,pop+1);       build.push(temp);       oper.pop_back();    }}int main(){    while(cin>>a>>b){       len =(int)a.length();       cout<<'['<<endl;       dfs(0,0);       cout<< ']' <<endl;    }    return 0;}