[백준 10866]

문제

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

10866번: 덱

---

내가 작성한 코드

import java.io.*;
import java.util.Deque;
import java.util.LinkedList;
import java.util.StringTokenizer;

public class qor10866 {
    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));

        int num = Integer.parseInt(br.readLine());
        Deque<Integer> nums = new LinkedList<>();

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

            if(word.equals("push_front")){
                int number = Integer.parseInt(st.nextToken());

                nums.addFirst(number);
            }
            else if(word.equals("push_back")){
                int number = Integer.parseInt(st.nextToken());

                nums.addLast(number);
            }
            else if(word.equals("pop_front")){
                if(nums.isEmpty()){
                    bw.write("-1"+"\n");
                }
                else{
                    bw.write(nums.pollFirst()+"\n");
                }
            }
            else if(word.equals("pop_back")){
                if(nums.isEmpty()){
                    bw.write("-1"+"\n");
                }
                else{
                    bw.write(nums.pollLast()+"\n");
                }
            }
            else if(word.equals("size")){
                bw.write(nums.size()+"\n");
            }
            else if(word.equals("empty")){
                if(nums.isEmpty()){
                    bw.write("1"+"\n");
                }
                else{
                    bw.write("0"+"\n");
                }
            }
            else if(word.equals("front")){
                if(nums.isEmpty()){
                    bw.write("-1"+"\n");
                }
                else{
                    bw.write(nums.peekFirst()+"\n");
                }
            }
            else{
                if(nums.isEmpty()){
                    bw.write("-1"+"\n");
                }
                else{
                    bw.write(nums.peekLast()+"\n");
                }
            }
        }

        bw.close();
    }
}