[백준,c++] 10845번 - 큐

10845번: 큐

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

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(0);

    int N; cin >> N;
    queue<int>q;
    while (N--) {
        string s; cin >> s;
        if (s == "push") {
            int num; cin >> num;
            q.push(num);
        }
        else if (s == "pop") {
            if (q.empty()) cout << -1 << "\n";
            else {
                cout << q.front() << "\n";
                q.pop();
            }
        }
        else if (s == "size") cout << q.size() << "\n";
        else if (s == "empty") {
            if (q.empty()) cout << 1 << "\n";
            else cout << 0 << "\n";
        }
        else if (s == "front") {
            if (q.empty()) cout << -1 << "\n";
            else cout << q.front() << "\n";
        }
        else if (s == "back") {
            if (q.empty())cout << -1 << "\n";
            else cout << q.back() << "\n";
        }
    }
}