[알고리즘] 백준 - 10845번 : 큐

알고리즘 문제 출처 : https://www.acmicpc.net/problem/10845

10845번: 큐

 

내가 작성한 코드

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.util.LinkedList;

public class Main {
	
	public static void main(String[] args) throws NumberFormatException, IOException {
		LinkedList<Integer> queue = new LinkedList<>();
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
		StringBuilder sb = new StringBuilder();
		int n = Integer.parseInt(br.readLine());
		for(int i=0; i<n; i++) {
			String[] cmd = br.readLine().split(" ");
			if(cmd[0].equals("push")) {
				queue.add(Integer.parseInt(cmd[1]));
			}//push
			else if(cmd[0].equals("pop")) {
				if(!queue.isEmpty()) {
					sb.append(queue.poll()+"\n");
				}else {
					sb.append(-1+"\n");
				}
			}//pop
			else if(cmd[0].equals("size")) {
				sb.append(queue.size()+"\n");
			}//size
			else if(cmd[0].equals("empty")) {
				if(queue.isEmpty()) {
					sb.append(1+"\n");
				}else {
					sb.append(0+"\n");
				}
			}//empty
			else if(cmd[0].equals("front")) {
				if(!queue.isEmpty()) {
					sb.append(queue.getFirst()+"\n");
				}else {
					sb.append(-1+"\n");
				}
			}//front
			else if(cmd[0].equals("back")) {
				if(!queue.isEmpty()) {
					sb.append(queue.getLast()+"\n");
				}else {
					sb.append(-1+"\n");
				}
			}//back
		}//for
		bw.write(sb.toString());
		bw.flush();
		bw.close();
	}
}