题解

#include <iostream>
using namespace std;
void beforder(string in, string aft)
{
    if (in.size() > 0)  
    {
        char root = aft[aft.length() - 1];
        string in1 = in.substr(0, in.find(root));
        string in2 = in.substr(in.find(root) + 1);
        cout << root;
        beforder(in1, aft.substr(0, in.find(root)));
        beforder(in2, aft.substr(in.find(root), in.size() - in.find(root) - 1));
    }
}

int main()
{
    string inorder, aftorder;
    cin >> inorder >> aftorder;
    beforder(inorder, aftorder);
}