18258번 큐 2 - C++

[문제]
https://www.acmicpc.net/problem/18258

18258번: 큐 2

[풀이]
기본 큐 문제

[코드]

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

int main() {
    ios::sync_with_stdio(0);
    cin.tie(0);
    
    queue<int> q;
    int n;
    cin >> n;
    while(n--){
        string s;
        cin >> s;
        if(s == "push") {
            int n;
            cin >> n;
            q.push(n);
        }
        else if(s == "pop"){
            if(!q.empty()) {
                cout << q.front() << '\n';
                q.pop();
            }
            else {
                cout << -1 << '\n';
            }
        }
        else if(s == "size") cout << q.size() << '\n';
        
        else if(s == "empty") cout << q.empty() << '\n';
        
        else if(s == "front") {
            if(!q.empty()) cout << q.front() << '\n';
            else cout << -1 << '\n';
        }
        else {
            if(!q.empty()) cout << q.back() << '\n';
            else cout << -1 << '\n';
        }
    }
}