백준 소스코드 [C++] 18258 큐 2

www.acmicpc.net/problem/18258

18258번: 큐 2

백준 소스코드 [C++] 18258 큐 2

#include <iostream>
#include <utility>
#include <vector>
#include <queue>
#include <string>
using namespace std;
int main() {
	ios_base::sync_with_stdio(false);
	cin.tie(NULL);
	int n,m;
	cin >> n;
	queue <int> q;
	string xx;
	for (int i = 0;i < n;i++) {
		cin >> xx;
		if (xx == "push") {
			cin >> m;
			q.push(m);
		}
		else if (xx == "front") {
			if (q.empty() == true) cout << "-1" << '\n';
			else {
				cout << q.front() << '\n';
			}
		}
		else if (xx == "back") {
			if (q.empty() == true) cout << "-1" << '\n';
			else {
				cout << q.back() << '\n';
			}
		}
		else if (xx == "size") cout << q.size() << '\n';
		else if (xx == "empty") cout << q.empty() << '\n';
		else if (xx == "pop") {
			if (q.empty() == true) cout << "-1" << '\n';
			else {
				cout << q.front() << '\n';
				q.pop();
			}
		}
	}
	return 0;
}