[goormlevel/Java] Queue

-Code

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

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

		int n = Integer.parseInt(st.nextToken());
		int k = Integer.parseInt(st.nextToken());

		Deque<Integer> deq = new ArrayDeque<>();

		for (int i = 0; i < n; i++) {
			st = new StringTokenizer(br.readLine());
			// 명령어 받기
			String comm = st.nextToken();
			// 각 명령어 처리
			if (comm.equals("pop")) {
				// 비어있는지 확인
				if (deq.isEmpty()) {
					System.out.println("Underflow");			
				} else {
					System.out.println(deq.pollFirst());		
				}
			} else {
				// 크기를 넘어가는지 확인
				if (deq.size() == k) {
					System.out.println("Overflow");		
				} else {
					deq.addLast(Integer.parseInt(st.nextToken()));
				}
			}
		}
	}
}