题解 | 【模板】栈的操作

#include <iostream>
#include<stack>
using namespace std;
void solve(){
    stack<int> stk;
    int t;
    cin>>t;
    string s1;
    int num2;
    while(t--){
        cin>>s1;
        if(s1 =="push"){
            cin>>num2;
            stk.push(num2);
        }else if(s1 == "pop"){
            if(stk.empty()){
                cout<<"Empty"<<endl;
            }else{
                stk.pop();
            }
        }else if(s1 == "query"){
            if(stk.empty()){
                cout<<"Empty"<<endl;
            }else{
                cout<<stk.top()<<endl;
            }
        }else if(s1 == "size"){
            cout<<stk.size()<<endl;
        }
    }
}
int main() {
    solve();
    return 0;
}