백준_10845: 큐

 

www.acmicpc.net/problem/10845

10845번: 큐

 

#define _CRT_SECURE_NO_WARNINGS
#include <iostream>
#include <queue>
#include <string>
#include <string.h>			//스트링 자를때 필요한 헤더파일
using namespace std;

int main() {
	queue<int> q;
	int n, number;
	string s;

	ios_base::sync_with_stdio(false);	//cin, cout 시간초과 해결코드
	cin.tie(NULL);
	cout.tie(NULL);

	cin >> n;

	for (int i = 0; i < n; i++) {
	
		cin >> s;
		
		if (s == "push") {	
			cin >> number;
			q.push(number);

		}
		else if (s == "pop") {
			if (q.empty() == false) {		//큐가 차있을때
				cout << q.front() << "\n";
				q.pop();
			}
			else							//큐가 비어있을 때
				cout << "-1" << "\n";	
		}

		else if (s == "size")
			cout << q.size() << "\n";

		else if (s == "empty") {
			if (q.empty() == true)
				cout << "1\n";
			else
				cout << "0\n";
		}

		else if (s == "front") {
			if (q.empty() == true)
				cout << "-1\n";
			else
				cout << q.front() << "\n";
		}

		else if (s == "back") {
			if (q.empty() == true)
				cout << "-1\n";
			else
				cout << q.back() << "\n";
		}

	}

	return 0;
}