[백준] 큐(10843)

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

✅ 코드

import java.io.*;
import java.util.*;

public class 백준_10845 {
    static int n;
    public static void main(String[] args) throws Exception {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        StringTokenizer st = new StringTokenizer(br.readLine());

        n = Integer.parseInt(st.nextToken());
        Deque<Integer> deque = new ArrayDeque<>();

        for(int i = 0; i < n ; i++){
            st = new StringTokenizer(br.readLine());
            String order = st.nextToken();

            if(order.equals("push")){
                int num = Integer.parseInt(st.nextToken());
                deque.offer(num);
            }
            else if(order.equals("pop")){
                if(deque.size() == 0){
                    System.out.println("-1");
                }
                else{
                    System.out.println(deque.poll());
                }
            }
            else if(order.equals("size")){
                System.out.println(deque.size());
            }
            else if(order.equals("empty")){
                if(deque.size() == 0){
                    System.out.println("1");
                }
                else{
                    System.out.println("0");
                }
            }
            else if(order.equals("front")){
                if(deque.size() == 0){
                    System.out.println("-1");
                }
                else{
                    System.out.println(deque.peek());
                }
            }
            else if(order.equals("back")){
                if(deque.size() == 0){
                    System.out.println("-1");
                }
                else{
                    System.out.println(deque.peekLast());
                }
            }
        }
    }
}

💡 배운 점 & 느낀 점

1. Deque<Integer> deque → Java는 Queue와 Deque 자료구조를 지원한다.