题解 | 【模板】栈的操作

#include <iostream>
#include <vector>
using namespace std;

int main() {
    int n;
    cin >> n;
    vector<int> v;
    for (int i=0;i<n;i++){
        string operate;
        cin >> operate;
        if (operate=="push"){
            long long int x;
            cin>>x;
            v.push_back(x);
            continue;
        }
        if (operate=="pop"){
            if (v.size()==0){cout<<"Empty"<<endl;}
            else{v.pop_back();}
            continue;
        }
        if (operate=="query"){
            if (v.size()==0){cout<<"Empty"<<endl;}
            else{cout<<v.back()<<endl;}
            continue;
        }
        if (operate=="size"){
            cout<<v.size()<<endl;
            continue;
        }
    }

}
// 64 位输出请用 printf("%lld")