[10866] 덱 - Java

 

1. 문제

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

10866번: 덱

 

2. 풀이

 

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

public class Main {
	
	public static LinkedList<Integer> deque = new LinkedList();
	private static int size;
	
	public static void main(String[] args) throws NumberFormatException, IOException {
		
		// 1. Read command
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		int N = Integer.parseInt(br.readLine());
		
		// 2. Execute command
		String command;
		StringBuilder sb = new StringBuilder();
		StringTokenizer st;
		size = 0;
		
		for(int i = 0; i < N; i++) {
			
			st = new StringTokenizer(br.readLine(), " ");
			
			command = st.nextToken();
			switch(command) {
				
			case "push_front":
				push_front(Integer.parseInt(st.nextToken()));
				break;
			case "push_back":
				push_back(Integer.parseInt(st.nextToken()));
				break;
			case "pop_front":
				sb.append(pop_front()).append('\n');
				break;
			case "pop_back":
				sb.append(pop_back()).append('\n');
				break;
			case "size":
				sb.append(size()).append('\n');
				break;
			case "empty":
				if(empty()) {
					sb.append(1).append('\n');
				}else {
					sb.append(0).append('\n');
				}
				
				break;
			case "front":
				sb.append(front()).append('\n');
				break;
			case "back":
				sb.append(back()).append('\n');
				break;
			default:
				break;
			}
		}
		// 3. Print result
		System.out.println(sb);
	}
	
	// push_front
	public static void push_front(int num) {
		deque.addFirst(num);
	}
	
	// push_back
	public static void push_back(int num) {
		deque.addLast(num);
	}
	
	// pop_front
	public static int pop_front() {
		if(empty()) {
			return -1;
		}
		return deque.pollFirst();
	}

	// pop_back
	public static int pop_back() {
		if(empty()) {
			return -1;
		}
		return deque.pollLast();
	}
	
	// size
	public static int size() {
		return deque.size();
	}
	
	// empty
	public static boolean empty() {
		return size() == 0;
	}
	
	// front
	public static int front() {
		if(empty()) {
			return -1;
		}
		return deque.getFirst();
	}
	
	// back
	public static int back() {
		if(empty()) {
			return -1;
		}
		return deque.getLast();
	}
}

 

3. 배운점

 

 

4. 개선할 점