[Baekjoon Online Judge] 2667 - 단지번호붙이기 / Java

https://www.acmicpc.net/problem/2667

2667번: 단지번호붙이기

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.Collections;

public class Main {

	static int N;
	static int cnt; // 연결된 집의 수
	static int[][] map;
	static ArrayList<Integer> list = new ArrayList<>();
	static int[] dr = { -1, 1, 0, 0 };
	static int[] dc = { 0, 0, -1, 1 };

	public static void main(String[] args) throws Exception {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		N = Integer.parseInt(br.readLine());
		map = new int[N][N];

		for (int i = 0; i < N; i++) {
			String str = br.readLine();
			for (int j = 0; j < N; j++) {
				map[i][j] = str.charAt(j) - '0';
			}
		}

		for (int i = 0; i < N; i++) {
			for (int j = 0; j < N; j++) {
				if (map[i][j] == 1) {
					cnt = 0;
					dfs(i, j);

					// 단지의 크기가 1개인 경우 1
					list.add(cnt == 0 ? 1 : cnt);
				}
			}
		}

		Collections.sort(list);
		System.out.println(list.size());
		for (int i = 0; i < list.size(); i++) {
			System.out.println(list.get(i));
		}
	}

	private static void dfs(int r, int c) {
		for (int dir = 0; dir < 4; dir++) {
			int nr = r + dr[dir];
			int nc = c + dc[dir];

			if ((nr >= 0 && nr < N && nc >= 0 && nc < N) && map[nr][nc] == 1) {
				map[nr][nc] = 2;
				cnt++;
				dfs(nr, nc);
			}
		}
	}
}