[JAVA 백준 문제풀이] 얼렁뚱땅 18258 큐2 풀이

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

18258번: 큐 2

 

### 시간초과 ###

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


public class Main {

	public static void main(String[] args) throws IOException {
		// TODO Auto-generated method stub
		
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		int n = Integer.parseInt(br.readLine());
		Deque<String> dq = new LinkedList<String>();
		for(int i=0;i<n;i++) {
			String [] str = br.readLine().split(" ");
			if (str[0].equals("push")) {
				dq.add(str[1]);
			} else if(str[0].equals("front")) {
				if(dq.isEmpty()) {
					System.out.println(-1);
				} else {
					System.out.println(dq.getFirst());
				}
			} else if(str[0].equals("pop")) {
				if(dq.isEmpty()) {
					System.out.println(-1);
				} else {
					System.out.println(dq.pop());
				}
			} else if(str[0].equals("size")) {
				System.out.println(dq.size());
			} else if(str[0].equals("empty")) {
				if(dq.isEmpty()) {
					System.out.println(1);
				} else {
					System.out.println(0);
				}
			} else if(str[0].equals("back")) {
				if(dq.isEmpty()) {
					System.out.println(-1);
				} else {
					System.out.println(dq.getLast());
				}
			}
		}
		
	}

}

 

## 정답 ##

StringBuilder를 사용하여, 출력 할 곳을 sb에 모아주고 한방에 출력해야지만

시간초과가 뜨지 않음

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


public class Main {

	public static void main(String[] args) throws IOException {
		// TODO Auto-generated method stub
		
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		int n = Integer.parseInt(br.readLine());
		StringBuilder sb = new StringBuilder();
		
		Deque<String> dq = new LinkedList<String>();
		for(int i=0;i<n;i++) {
			String [] str = br.readLine().split(" ");
			if (str[0].equals("push")) {
				dq.add(str[1]);
			} else if(str[0].equals("front")) {
				if(dq.isEmpty()) {
					sb.append(-1).append("\n");
				} else {
					sb.append(dq.getFirst()).append("\n");
				}
			} else if(str[0].equals("pop")) {
				if(dq.isEmpty()) {
					sb.append(-1).append("\n");
				} else {
					sb.append(dq.pop()).append("\n");
				}
			} else if(str[0].equals("size")) {
				sb.append(dq.size()).append("\n");;
			} else if(str[0].equals("empty")) {
				if(dq.isEmpty()) {
					sb.append(1).append("\n");;
				} else {
					sb.append(0).append("\n");;
				}
			} else if(str[0].equals("back")) {
				if(dq.isEmpty()) {
					sb.append(-1).append("\n");
				} else {
					sb.append(dq.getLast()).append("\n");
				}
			}
		}
		System.out.println(sb);
		
	}

}