백준 7576번 토마토 [ Java ]

7576번: 토마토

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

public class Main {
    public static void main(String[] args) throws IOException{
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        Queue<int[]> Q = new LinkedList<>();
        int[] dx = new int[]{1, 0, -1, 0};
        int[] dy = new int[]{0, 1, 0, -1};
        int[] nm = Arrays.stream(br.readLine().split(" ")).mapToInt(Integer::parseInt).toArray();
        int N = nm[1], M = nm[0];
        String[][] field = new String[N][M];
        int[][] dist = new int[N][M];
        for (int i=0; i<N; i++) {
            String[] in = br.readLine().split(" ");
            for (int j=0; j<M; j++){
                field[i][j] = in[j];
                if (field[i][j].equals("1")) Q.offer(new int[]{i, j});
                if (field[i][j].equals("0")) dist[i][j] = -1;
            }
        }
        while (!Q.isEmpty()){
            int[] cur = Q.poll();
            for (int dir = 0; dir<4; dir++){
                int nx = cur[1] + dx[dir];
                int ny = cur[0] + dy[dir];
                if (nx < 0 || nx >=  M || ny < 0 || ny >= N) continue;
                if (dist[ny][nx] >= 0 ) continue;
                dist[ny][nx] = dist[cur[0]][cur[1]]+1;
                Q.offer(new int[]{ny, nx});
            }
        }
        int result = 0;
        for (int[] i : dist)
            for (int j : i){
                if (j == -1) {
                    System.out.print(-1);
                    System.exit(0);
                }
                result = Math.max(result, j);
            }
        System.out.print(result);
    }
}