题解 | 【模板】栈

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

typedef long long LL;
typedef unsigned long long ULL;
typedef pair<int,int> PII;

#define endl '\n'
#define nl cout << '\n'
#define den(a) cout << #a << " = " << a << '\n';
#define deg(a) cout << #a << " = " << a << "  ";
#define yes() cout << "Yes\n"
#define no() cout << "No\n"

const int N = 2e5 + 10, Mod = 998244353;


void solve() {
    int n;
    cin >> n;
    stack<int> q;
    while (n --) {
        string op;
        cin >> op;
        if(op == "push") {
            int x;
            cin >> x;
            q.push(x);
        } else if(op == "pop") {
            if(q.size()) {
                cout << q.top() << endl;
                q.pop();
            } else cout << "error" << endl;
        } else {
            if(q.size()) {
                cout << q.top() << endl;
            } else cout << "error" << endl;
        }
    }
}


int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    cout.tie(nullptr);
    int t = 1;
    //cin >> t;
    while (t--)solve();
    return 0;
}

直接用C++自带的stack即可