[백준] 2636번 치즈 #Java

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


class Point{
    int x,y;
    Point(int x,int y){
        this.x = x;
        this.y = y;
    }
}

public class Main {

    static int [][] board,check;
    static int cnt;
    static int[] dx = {1,0,-1,0};
    static int[] dy = {0,1,0,-1};
    static int n,m;
    public static void main(String[] args) throws Exception {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        StringTokenizer st = new StringTokenizer(br.readLine()," ");
        n = Integer.parseInt(st.nextToken());
        m = Integer.parseInt(st.nextToken());

        board = new int[n][m];
        check = new int[n][m];
        cnt = 0;

        for (int i = 0; i < n; i++) {
            st = new StringTokenizer(br.readLine()," ");
            for (int j = 0; j < m; j++) {
                board[i][j] = Integer.parseInt(st.nextToken());
                if(board[i][j]==1){
                    cnt++;
                }
            }
        }
        bfs();
    }

    private static void printMap(){
        for (int i = 0; i < n; i++) {
            for (int j = 0; j < m; j++) {
                System.out.print(board[i][j]+" ");
            }
            System.out.println();
        }
        System.out.println();
    }

    private static void bfs() {
        Queue<Point> q = new LinkedList<>();
        int day = 1;
        while (true) {
            q.offer(new Point(0,0));
           // System.out.println(day + " 일차");
           // printMap();
            check = new int[n][m];
            int deleteElement = 0;
            while (!q.isEmpty()) {
                Point poll = q.poll();
                int x = poll.x;
                int y = poll.y;

                check[x][y] = 1;

                for (int i = 0; i < 4; i++) {
                    int nx = x + dx[i];
                    int ny = y + dy[i];

                    if (0 <= nx && nx < n && 0 <= ny && ny < m) {
                        if (board[nx][ny] == 1 && check[nx][ny] == 0) {
                            board[nx][ny] = 2;
                            check[nx][ny] = 1;
                            deleteElement++;
                        }
                        if (board[nx][ny] == 0 && check[nx][ny] == 0) {
                            q.offer(new Point(nx, ny));
                            check[nx][ny] = 1;
                        }
                    }
                }

            }
            //printMap();
            if (deleteElement == cnt) {
                System.out.println(day);
                System.out.println(cnt);
                return;
            } else {
                deleteOld();
                cnt -= deleteElement;
                day++;
            }
            //printMap();
        }
    }

    private static void deleteOld() {
        for (int i = 0; i < n; i++) {
            for (int j = 0; j < m; j++) {
                if(board[i][j]==2){
                    board[i][j] = 0;
                }
            }
        }
    }
}