[백준 10845] 큐

문제

10845번: 큐

 

코드

package queue;

import java.util.ArrayList;
import java.util.Scanner;

class Queue{
	ArrayList<Integer> queue;
	
	public Queue() {
		queue=new ArrayList<Integer>();
	}
	
	public void push(int X) {
		queue.add(X);
	}
	
	public int pop() {
		if(this.size()>0) {
			return queue.remove(0);
		}
		else {
			return -1;
		}
	}
	
	public int size() {
		return queue.size();
	}
	
	public int empty() {
		if(this.size()<1) {
			return 1;
		}
		else {
			return 0;
		}
	}
	public int front() {
		if(this.size()>0) {
			return queue.get(0);
		}
		else {
			return -1;
		}
	}
	public int back() {
		if(this.size()>0) {
			return queue.get(this.size()-1);
		}
		else {
			return -1;
		}
	}
	
}
public class QueueDemo {
	public static void main(String[] args) {
		Queue queue=new Queue();
		Scanner in=new Scanner(System.in);
		int N=in.nextInt();
		
		for(int i=0;i<N;i++) {
			String command=in.next();
			
			if(command.equals("push")) {
				int num=in.nextInt();
				queue.push(num);
			}
			else if(command.equals("pop")) {
				System.out.println(queue.pop());
			}
			else if(command.equals("size")) {
				System.out.println(queue.size());
			}
			else if(command.equals("empty")) {
				System.out.println(queue.empty());
			}
			else if(command.equals("front")) {
				System.out.println(queue.front());
			}
			else if(command.equals("back")) {
				System.out.println(queue.back());
			}
			else {
				System.out.println("코드 다시 짜3");
			}
			
		}
	}
}