[백준] 10866번 덱

https://www.acmicpc.net/problem/10866

10866번: 덱

 

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

public class Main {

    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner(System.in);
        StringBuffer sb = new StringBuffer();
        Deque<Integer> deque = new LinkedList<>();

        int N = sc.nextInt();

        for(int i = 0; i < N; i++) {
            String text = sc.next();

            switch(text) {
                case "push_front": 
                    deque.addFirst(sc.nextInt());
                    break;
                case "push_back":
                    deque.addLast(sc.nextInt());
                    break;
                case "pop_front":
                    if(deque.isEmpty()) {
                    	sb.append(-1).append("\n");
                    } else {
                    	sb.append(deque.removeFirst()).append("\n");
                    }
                    break;
                case "pop_back":
                    if(deque.isEmpty()) {
                    	sb.append(-1).append("\n");
                    } else {
                    	sb.append(deque.removeLast()).append("\n");
                    }
                    break;
                case "size":
                    sb.append(deque.size()).append("\n");
                    break;
                case "empty":
                    if(deque.isEmpty()) {
                    	sb.append(1).append("\n");
                    } else {
                    	sb.append(0).append("\n");
                    }
                    break;
                case "front": 
                    if(deque.isEmpty()) {
                    	sb.append(-1).append("\n");
                    } else {
                    	sb.append(deque.peekFirst()).append("\n");
                    }
                    break;
                case "back":
                    if(deque.isEmpty()) {
                    	sb.append(-1).append("\n");
                    } else {
                    	sb.append(deque.peekLast()).append("\n");
                    }
                    break;
            }
        }
        System.out.println(sb);
    }

}