利用栈，将字符串输入得每个字符入栈，出栈得顺序为字符串的相反字符串！

#include<bits/stdc++.h>
using namespace std;


int main(){
    stack<char> s;
    string s1;
    cin >> s1;
    int flag = 1;
    char c;
    for(int i =0;i<s1.size();i++){
        s.push(s1[i]);
    }
    for(int i = 0;i<s1.size();i++){
         c = s.top();
        if(c != s1[i]){
            flag = 0;
        }
        s.pop();
    }
    if(flag == 1){
        cout << "yes";
    }else
        cout << "no";
}