[JAVA] 백준 18258번- 큐2

https://www.acmicpc.net/problem/18258

18258번: 큐 2

 

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.Deque;
import java.util.LinkedList;
import java.util.StringTokenizer;

public class Main{
    public static void main(String[] args) throws IOException {
        BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
        Deque<Integer> q=new LinkedList<>();
        int n=Integer.parseInt(br.readLine());
        StringBuilder sb = new StringBuilder();

        while(n-- > 0){
            StringTokenizer st=new StringTokenizer(br.readLine());
            String str=st.nextToken();

            switch(str){
                case "push":
                    q.offer(Integer.parseInt(st.nextToken()));
                    break;

                case "pop":
                    if(q.isEmpty()) sb.append(-1).append("\n");
                    else sb.append(q.poll()).append("\n");
                    break;

                case "size":
                    sb.append(q.size()).append("\n");
                    break;

                case "empty":
                    if(q.isEmpty()) sb.append(1).append("\n");
                    else sb.append(0).append("\n");
                    break;

                case "front":
                    if(q.isEmpty())sb.append(-1).append("\n");
                    else sb.append(q.peek()).append("\n");
                    break;

                case "back":
                    if(q.isEmpty()) sb.append(-1).append("\n");
                    else sb.append(q.peekLast()).append("\n");
                    break;
            }
        }
        System.out.println(sb);
    }
}

 

 

큐에 양쪽에 데이터를 넣고 뺄수 있는 자료구조인 덱을 사용한다.