非常简短清晰的代码

C++ 代码

#include <bits/stdc++.h>

using namespace std;

const int N = 1e5 + 10;

int n, x;
int q[N], tt = -1, hh;

int main()
{
    cin >> n;

    while (n --)
    {
        string op;
        cin >> op;
        if (op == "push") cin >> q[ ++ tt];
        else if (op == "pop") hh ++;
        else if (op == "query")cout << q[hh] << "\n";
        else if(hh <= tt) cout << "NO\n";
        else cout << "YES\n";
    }

    return 0;
}