贴个代码吧

#include <iostream>
#include <iomanip>
#include <string>
#include <algorithm>
#include <cmath>
#include <string>
#include <list>
#include <map>
#include <set>
#include <queue>
#include <vector>
#include <stack>
using namespace std;
string preOrder,inOrder;
void postOrder(int prel,int prer,int inl,int inr)
{
    if(prel>prer)
        return ;
    char root;
    root=preOrder[prel];
    int ind=inl;
    for(int i=inl;i<=inr;i++)
    {
        if(inOrder[i]==root)
        {
            ind=i;
            break;
        }
       
    }
    postOrder(prel+1,ind-inl+prel,inl,ind-1);
    postOrder(ind-inl+prel+1,prer,ind+1,inr);
    cout<<root;
}
int main(){
    cin>>preOrder>>inOrder;
    postOrder(0,preOrder.length()-1,0,inOrder.length()-1);
    
    
    
    return 0;
}