uva536 Tree Recovery

已知前序中序求后序

#include <iostream>#include <cstdio>#include <string>#include <cstring>using namespace std;string po;void Computing(string pre,string in){    int len=pre.length();    if(len>0){        int p=(int)(in.find(pre[0]));        Computing(pre.substr(1,p),in.substr(0,p));        Computing(pre.substr(p+1,len-p-1),in.substr(p+1,len-p));        po.push_back(pre[0]);    }}int main(){    string pre,in;    while(cin>>pre>>in){        Computing(pre,in);        cout<<po<<endl;        pre.clear();in.clear();po.clear();    }    return 0;}