토마토

https://www.acmicpc.net/problem/7576

7576번: 토마토

// 코드

import java.util.*;
import java.io.*;
 
public class Main{  
  
  // 상, 하, 좌, 우 
  static int[][] dir  = {{-1, 0}, {1, 0}, {0, -1}, {0, 1}};
  
  static int N, M;
  static int[][] arr;
  static int[][] result;
  
  static int BFS() {
    
    Deque<int[]> deq = new LinkedList<>();
    
    for(int i=0; i<N; i++) {
      for(int j=0; j<M; j++) {
        if(arr[i][j] == 1) deq.add(new int[]{i, j}); 
      }
    }
    
    while(!deq.isEmpty()) {
      int[] getV = deq.pop();
    
      for(int i=0; i<4; i++) {
        // 상, 하, 좌, 우
        int ny = dir[i][0] + getV[0];
        int nx = dir[i][1] + getV[1];
        
        if((0 <= ny && ny < N) && (0 <= nx && nx < M) && (arr[ny][nx] == 0)) {
          arr[ny][nx] = arr[getV[0]][getV[1]] + 1;
          deq.add(new int[]{ny, nx});
        }
        
      }  
    } 
    
    int result = Integer.MIN_VALUE; 
    for(int[] ar1 : arr) {
      for(int ar2 : ar1) {
        if(ar2 == 0) return -1;
        result = Math.max(result, ar2);
      }
    }
    
    if(result == 1) return 0;
    else return result - 1;
  }
  
  // main
  public static void main(String[] args) throws Exception {
    
    BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
    BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); 
    StringTokenizer st = new StringTokenizer(br.readLine());
    
    M = Integer.parseInt(st.nextToken());
    N = Integer.parseInt(st.nextToken());
    
    arr    = new int[N][M];
    result = new int[N][M];
    
    for(int i=0; i<N; i++) {
      arr[i] = Arrays.stream(br.readLine().split(" ")).mapToInt(Integer::parseInt).toArray();
    } 
    
    int resVal = BFS();
    
    bw.write(String.valueOf(resVal));
    br.close();
    bw.flush();
    bw.close();
  }
}