蒟蒻求助

#include<bits/stdc++.h>
using namespace std;
string middle,back;
void find(string middle,string back){
    if(middle.length()>0){
        char t=back[back.length()-1];
        int root=middle.find(t);
        cout<<t;
        string middleleft=middle.substr(0,root-1),middleright=middle.substr(root+1,middle.length()-1);
        string backleft=back.substr(0,root-1),backright=back.substr(root+1,middle.length()-root-2);
        find(middleleft,backleft);find(middleright,backright);
    }
}
int main(){
    cin>>middle>>back;
    find(middle,back);
    return 0;
}