[JAVA-자바] 14502번: 연구소

 

소스코드:

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.LinkedList;
import java.util.List;
import java.util.Queue;
import java.util.StringTokenizer;

public class Main {
    static BufferedReader br;
    static BufferedWriter bw;

    static int height, width;
    static int[][] board;
    static List<int[]> viruses;
    static int safeCount;
    static int result;

    static final int[] dy = {-1, 1, 0, 0};
    static final int[] dx = {0, 0, -1, 1};

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

        StringTokenizer st = new StringTokenizer(br.readLine());
        height = Integer.parseInt(st.nextToken());
        width = Integer.parseInt(st.nextToken());

        board = new int[height][width];
        viruses = new ArrayList<>();
        safeCount = 0;
        result = 0;

        for (int y = 0; y < height; y++) {
            st = new StringTokenizer(br.readLine());
            for (int x = 0; x < width; x++) {
                board[y][x] = Integer.parseInt(st.nextToken());
                if (board[y][x] == 2) { // virus
                    viruses.add(new int[]{y, x});
                } else if (board[y][x] == 0) {
                    safeCount++;
                }
            }
        }
        br.close();
        makeWalls(0);
        bw.write(result + "\n");
        bw.close();
    }

    public static void bfs() {
        int[][] temp_board = new int[height][width];
        for (int y = 0; y < height; y++) {
            temp_board[y] = Arrays.copyOf(board[y], board[y].length);
        }

        Queue<int[]> queue = new LinkedList<>(viruses);
        int count = 0;

        while (!queue.isEmpty()) {
            int[] cur = queue.poll();

            for (int i = 0; i < 4; i++) {
                int addY = cur[0] + dy[i];
                int addX = cur[1] + dx[i];

                if (isValidPosition(addY, addX) && temp_board[addY][addX] == 0) {
                    temp_board[addY][addX] = 2;
                    count++;
                    queue.add(new int[]{addY, addX});
                }
            }
        }

        int calc = safeCount - count - 3;
        result = Math.max(result, calc);
    }

    public static boolean isValidPosition(int y, int x) {
        return y >= 0 && y < height && x >= 0 && x < width;
    }

    public static void makeWalls(int count) {
        if (count == 3) {
            bfs();
            return;
        }

        for (int y = 0; y < height; y++) {
            for (int x = 0; x < width; x++) {
                if (board[y][x] == 0) {
                    board[y][x] = 1;
                    makeWalls(count + 1);
                    board[y][x] = 0; // backtrack
                }
            }
        }

    }

}

 

글의 내용 중 잘못된 점이나 수정이 필요한 부분, 혹은 궁금한 사항이 있다면 언제든 댓글로 남겨주시면 감사하겠습니다.

여러분의 피드백은 더 나은 글을 작성하는 데 큰 도움이 됩니다. 감사합니다.