[BOJ] 2234 성곽 (JAVA)

https://www.acmicpc.net/problem/2234

2234번: 성곽

방 개수를 세면서 각 방마다 번호를 지정하고 풀었습니다.

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

public class Main {
	
    static BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    static StringTokenizer st;
    static int N, M, number, cnt, maxCnt, maxSum;
    static int[] size;
    static int[][] map, mark;
    static int[] dr = {  0, -1,  0,  1 };
    static int[] dc = { -1,  0,  1,  0 };

    public static void main(String[] args) throws Exception {

        st = new StringTokenizer(br.readLine(), " ");
        M = Integer.parseInt(st.nextToken());
        N = Integer.parseInt(st.nextToken());
        size = new int[2501];
        map = new int[N][M];
        mark = new int[N][M];
        for (int i = 0; i < N; i++) {
            st = new StringTokenizer(br.readLine(), " ");
            for (int j = 0; j < M; j++) {
               map[i][j] = Integer.parseInt(st.nextToken());
            }
        } // end of input

        Queue<int[]> q = new LinkedList<>();
        number = 1;

        for (int i = 0; i < N; i++) {
            for (int j = 0; j < M; j++) {
                if (mark[i][j] == 0) {
                    q.offer(new int[] { i, j });
                    mark[i][j] = number;
                    cnt = 1;
                    while (!q.isEmpty()) {
                        int[] a = q.poll();
                        for (int dir = 0; dir < 4; dir++) {
                            int nr = a[0] + dr[dir];
                            int nc = a[1] + dc[dir];
                            if ((map[a[0]][a[1]] & (1 << dir)) == 0 && mark[nr][nc] == 0) {
                                cnt++;
                                q.offer(new int[] { nr, nc });
                                mark[nr][nc] = number;
                            }
                        }
                    }
                    size[number] = cnt;
                    number++;
                    maxCnt = Math.max(maxCnt, cnt);
                }
            }
        } // end of marking

        for (int i = 0; i < N; i++) {
            for (int j = 0; j < M; j++) {
                for (int dir = 2; dir < 4; dir++) {
                    int nr = i + dr[dir];
                    int nc = j + dc[dir];
                    if (nr < N && nc < M && mark[i][j] != mark[nr][nc]) {
                        int temp = size[mark[i][j]] + size[mark[nr][nc]];
                        maxSum = Math.max(maxSum, temp);
                    }
                }
            }
        }

        System.out.print(number - 1 + "\n" + maxCnt + "\n" + maxSum);

    }

}