题解 | #【模板】栈#

#include <iostream>
using namespace std;

const int N = 100010;

int main()
{
    int n;
    int stk[N],tt = -1;
    cin >> n;
    while(n--)
    {
        string op;
        cin >> op;
        if(op == "push")
        {
            int x;
            cin >> x;
            stk[ ++ tt] = x;
        }
        else if(op == "pop")
        {
           if(tt == -1)
                cout << "error" << endl;
            else
            {
                cout << stk[tt] << endl;
                tt --;
            }
        }
        else if(op == "top")
        {
            if(tt == -1)
                cout << "error" << endl;
            else
                cout << stk[tt] << endl;
        }
    }
    return 0;
}