题解 | 【模板】栈

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

int main() {
    int n ;
    cin>>n ;
    deque<int> a;
    for(int i = 0 ; i< n ;i++){
        string s;
        cin>>s;
       //cout<<s<<"@@@"<<endl;;
        if(s[1]=='u'){
            int t ;
            cin>>t;
            //cout<<t<<"----";
            a.push_back(t);
            continue;
        }
        if(s[0]=='p'&&s[1]=='o'){
            if(a.empty()){
                cout<<"error"<<endl;
                continue;
            }
            else{
            cout<<a.back()<<endl;;
            a.pop_back();
            continue;
            }
            
        }
        else{
            if(a.empty()){
                cout<<"error"<<endl;
                continue;
            }
            cout<<a.back()<<endl;
        }

    }

    return 0;
}
// 64 位输出请用 printf("%lld")

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