백준알고리즘 10845번 큐

백준알고리즘

https://www.acmicpc.net/problem/10845

Front만 유의하면 쉬운 문제

import java.util.LinkedList;
import java.util.Queue;
import java.util.Scanner;

public class Main{

    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        int count = Integer.parseInt(scan.next().trim());
        int lastValue = 0;
        
        Queue<Integer> que = new LinkedList<Integer>();
        
        for(int i=0; i <= count; i++) {
            String command = scan.nextLine().trim();
            
            if(command.contains("push")) {
                int data = Integer.parseInt(command.substring(5, command.length()));
                lastValue = data;
                que.offer(data);
            } else if(command.contains("pop")) {
                if(que.size() == 0) {
                    System.out.println(-1);
                } else {
                    System.out.println(que.poll());
                }
            } else if(command.contains("front")) {
                if(que.size() == 0) {
                    System.out.println(-1);
                } else {
                    System.out.println(que.peek());
                }
            } else if(command.contains("back")) {
                if(que.size() == 0) {
                    System.out.println(-1);
                } else {
                    System.out.println(lastValue);
                }
            } else if(command.contains("empty")) {
                if(que.size() == 0) {
                    System.out.println(1);
                } else {
                    System.out.println(0);
                }
            } else if(command.contains("size")) {
                System.out.println(que.size());
            }
        }
        scan.close();
    }
}