백준 2638번 : 치즈 Java

https://www.acmicpc.net/problem/2638

2638번: 치즈

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

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

    @Override
    public String toString() {
        return "(" + x + "," + y + ")";
    }
}

public class Main {

    static int dx[] = {1,0,-1,0};
    static int dy[] = {0,1,0,-1};
    static int map[][] = new int[101][101];

    static Queue<Point> Q = new LinkedList<>();
    static Queue<Point> willDisappear = new LinkedList<>();

    static boolean isContact(int x, int y){
        int cnt = 0;
        for(int i=0; i<4; i++){
            int nx = x + dx[i];
            int ny = y + dy[i];
            if(nx<0 || nx>n || ny<0 || ny>m) continue;
            if(map[nx][ny]==-1){
                cnt++;
            }
        }
        if(cnt>=2) return true;
        else return false;
    }

    static int n,m;

    static void spreadAir(){
        while(!Q.isEmpty()){
            Point cur = Q.poll();

            for(int i=0; i<4; i++){
                int nx = cur.x + dx[i];
                int ny = cur.y + dy[i];
                if(nx<0 || nx>n || ny<0 || ny>m) continue;
                if(map[nx][ny]==0){
                    map[nx][ny] = -1;
                    Q.add(new Point(nx, ny));
                }
            }
        }
    }

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        n = sc.nextInt();
        m = sc.nextInt();

        for(int i=0; i<n; i++){
            for(int j=0;j<m; j++){
                map[i][j] = sc.nextInt();
            }
        }

        Q.add(new Point(0,0));
        Q.add(new Point(0,m-1));
        Q.add(new Point(n-1,0));
        Q.add(new Point(n-1,m-1));
        spreadAir();

        int ans = 0;
        while(true){
            boolean flag = false;
            for(int i=0; i<n; i++){
                for(int j=0;j<m; j++){
                    if(map[i][j] == 1){
                        flag = true;
                        if(isContact(i,j)){
                            willDisappear.add(new Point(i,j));
                        }
                    }
                }
            }


            if(flag==false) break;

            while(!willDisappear.isEmpty()){
                Point curr = willDisappear.poll();
                map[curr.x][curr.y] = -1;
                Q.add(curr);
            }
            spreadAir();
            ans++;
        }

        System.out.println(ans);

    }
}