백준 2667 - 단지번호 붙이기(feat. java)

import java.util.ArrayList;
import java.util.Collections;
import java.util.LinkedList;
import java.util.Queue;
import java.util.Scanner;

public class Main {
	
	static int[][] map;
	static boolean[][] visited;
	static ArrayList list = new ArrayList();
	static int[] dx = {-1,1,0,0};
	static int[] dy = {0,0,-1,1};
	static int N;
	
	public static class Point {
		int x;
		int y;
		
		Point(int x, int y) {
			this.x = x;
			this.y = y;
		}
	}
	
	public static void bfs(int x, int y) {
		
		Queue<Point> q = new LinkedList<Point>();
		
		int local = 1;
		
		q.add(new Point(x,y));
		visited[x][y] = true;
		
		while(!q.isEmpty()) {
			
			Point p = q.poll();
			
			for (int i =0; i < 4; i++) {
				int nextX = p.x + dx[i];
				int nextY = p.y + dy[i];
				
				if (nextX < 0 || nextY <0 || nextX >= N || nextY >=N) continue;
				if (visited[nextX][nextY] || map[nextX][nextY] == 0) continue;
				
				
				q.add(new Point(nextX,nextY));
				
				visited[nextX][nextY] = true;
				
				local++;
				
			}
		}
		
		list.add(local);
	}
	
	public static void main(String[] args) {
		
		Scanner sc = new Scanner(System.in); 
		N = sc.nextInt();
		sc.nextLine();
		
		map = new int[N][N];
		visited = new boolean[N][N];
		
		int cnt = 0;
		
		for (int i = 0; i < N; i++) {
			String str = sc.nextLine();
			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 && visited[i][j] == false) {
					bfs(i,j);
					cnt++;
				}
				
			}
		}
		
		System.out.println(cnt);
		
		Collections.sort(list);
		
		for (int i = 0 ; i < list.size(); i++) {
			System.out.println(list.get(i));
		}
	}
}