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[BaekJoon] 10866 ๋ฑ JAVA

๐Ÿ”— ๋ฐฑ์ค€ 10866 ๋ฑ https://www.acmicpc.net/problem/10866

๋ฌธ์ œ

์ •์ˆ˜๋ฅผ ์ €์žฅํ•˜๋Š” ๋ฑ(Deque)๋ฅผ ๊ตฌํ˜„ํ•œ ๋‹ค์Œ, ์ž…๋ ฅ์œผ๋กœ ์ฃผ์–ด์ง€๋Š” ๋ช…๋ น์„ ์ฒ˜๋ฆฌํ•˜๋Š” ํ”„๋กœ๊ทธ๋žจ์„ ์ž‘์„ฑํ•˜์‹œ์˜ค.

๋ช…๋ น์€ ์ด ์—ฌ๋Ÿ ๊ฐ€์ง€์ด๋‹ค.

  • push_front X: ์ •์ˆ˜ X๋ฅผ ๋ฑ์˜ ์•ž์— ๋„ฃ๋Š”๋‹ค.
  • push_back X: ์ •์ˆ˜ X๋ฅผ ๋ฑ์˜ ๋’ค์— ๋„ฃ๋Š”๋‹ค.
  • pop_front: ๋ฑ์˜ ๊ฐ€์žฅ ์•ž์— ์žˆ๋Š” ์ˆ˜๋ฅผ ๋นผ๊ณ , ๊ทธ ์ˆ˜๋ฅผ ์ถœ๋ ฅํ•œ๋‹ค. ๋งŒ์•ฝ, ๋ฑ์— ๋“ค์–ด์žˆ๋Š” ์ •์ˆ˜๊ฐ€ ์—†๋Š” ๊ฒฝ์šฐ์—๋Š” -1์„ ์ถœ๋ ฅํ•œ๋‹ค.
  • pop_back: ๋ฑ์˜ ๊ฐ€์žฅ ๋’ค์— ์žˆ๋Š” ์ˆ˜๋ฅผ ๋นผ๊ณ , ๊ทธ ์ˆ˜๋ฅผ ์ถœ๋ ฅํ•œ๋‹ค. ๋งŒ์•ฝ, ๋ฑ์— ๋“ค์–ด์žˆ๋Š” ์ •์ˆ˜๊ฐ€ ์—†๋Š” ๊ฒฝ์šฐ์—๋Š” -1์„ ์ถœ๋ ฅํ•œ๋‹ค.
  • size: ๋ฑ์— ๋“ค์–ด์žˆ๋Š” ์ •์ˆ˜์˜ ๊ฐœ์ˆ˜๋ฅผ ์ถœ๋ ฅํ•œ๋‹ค.
  • empty: ๋ฑ์ด ๋น„์–ด์žˆ์œผ๋ฉด 1์„, ์•„๋‹ˆ๋ฉด 0์„ ์ถœ๋ ฅํ•œ๋‹ค.
  • front: ๋ฑ์˜ ๊ฐ€์žฅ ์•ž์— ์žˆ๋Š” ์ •์ˆ˜๋ฅผ ์ถœ๋ ฅํ•œ๋‹ค. ๋งŒ์•ฝ ๋ฑ์— ๋“ค์–ด์žˆ๋Š” ์ •์ˆ˜๊ฐ€ ์—†๋Š” ๊ฒฝ์šฐ์—๋Š” -1์„ ์ถœ๋ ฅํ•œ๋‹ค.
  • back: ๋ฑ์˜ ๊ฐ€์žฅ ๋’ค์— ์žˆ๋Š” ์ •์ˆ˜๋ฅผ ์ถœ๋ ฅํ•œ๋‹ค. ๋งŒ์•ฝ ๋ฑ์— ๋“ค์–ด์žˆ๋Š” ์ •์ˆ˜๊ฐ€ ์—†๋Š” ๊ฒฝ์šฐ์—๋Š” -1์„ ์ถœ๋ ฅํ•œ๋‹ค.

์ž…๋ ฅ

์ฒซ์งธ ์ค„์— ์ฃผ์–ด์ง€๋Š” ๋ช…๋ น์˜ ์ˆ˜ N (1 โ‰ค N โ‰ค 10,000)์ด ์ฃผ์–ด์ง„๋‹ค. ๋‘˜์งธ ์ค„๋ถ€ํ„ฐ N๊ฐœ์˜ ์ค„์—๋Š” ๋ช…๋ น์ด ํ•˜๋‚˜์”ฉ ์ฃผ์–ด์ง„๋‹ค. ์ฃผ์–ด์ง€๋Š” ์ •์ˆ˜๋Š” 1๋ณด๋‹ค ํฌ๊ฑฐ๋‚˜ ๊ฐ™๊ณ , 100,000๋ณด๋‹ค ์ž‘๊ฑฐ๋‚˜ ๊ฐ™๋‹ค. ๋ฌธ์ œ์— ๋‚˜์™€์žˆ์ง€ ์•Š์€ ๋ช…๋ น์ด ์ฃผ์–ด์ง€๋Š” ๊ฒฝ์šฐ๋Š” ์—†๋‹ค.


์ถœ๋ ฅ

์ถœ๋ ฅํ•ด์•ผํ•˜๋Š” ๋ช…๋ น์ด ์ฃผ์–ด์งˆ ๋•Œ๋งˆ๋‹ค, ํ•œ ์ค„์— ํ•˜๋‚˜์”ฉ ์ถœ๋ ฅํ•œ๋‹ค.


ํ’€์ด

์Šคํƒ ๋ฌธ์ œ ํ’€์ด : https://hyoreal.github.io/posts/BaekJoon-10828-%EC%8A%A4%ED%83%9D-JAVA/

deque๋Š” _first() / _Last() ๋ฉ”์„œ๋“œ๋ฅผ ์ง€์›ํ•œ๋‹ค.

์ด๋ฅผ ์‚ฌ์šฉํ•˜์—ฌ ์ฝ”๋“œ๋ฅผ ๊ตฌํ˜„ํ•˜์˜€๋‹ค.

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

public class Main {
    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        Deque<Integer> que = new ArrayDeque<>();
        StringBuilder sb = new StringBuilder();

        int n = Integer.parseInt(br.readLine());

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

            switch(s) {
                case "push_front" :
                    que.addFirst(Integer.parseInt(st.nextToken()));
                    break;
                case "push_back" :
                    que.addLast(Integer.parseInt(st.nextToken()));
                    break;
                case "pop_front" :
                    sb.append(que.isEmpty() ? -1 : que.removeFirst()).append("\n");
                    break;
                case "pop_back" :
                    sb.append(que.isEmpty() ? -1 : que.removeLast()).append("\n");
                    break;
                case "size" :
                    sb.append(que.size()).append("\n");
                    break;
                case "empty" :
                    sb.append(que.isEmpty() ? 1 : 0).append("\n");
                    break;
                case "front" :
                    sb.append(que.isEmpty() ? -1 : que.peekFirst()).append("\n");
                    break;
                case "back" :
                    sb.append(que.isEmpty() ? -1 : que.peekLast()).append("\n");
                    break;
            }
        }
        System.out.println(sb);
    }
}
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