백준 2468번 안전 영역 [ Java ]

2468번: 안전 영역

비가 안오는 경우의 반례를 주의해야 합니다

2

11

11

answer : 1

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

public class Main {

    public static void main(String[] args) throws IOException{
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        int[] dx = new int[]{1, 0, -1 ,0};
        int[] dy = new int[]{0, 1, 0, -1};
        int result = 0;
        int N = Integer.parseInt(br.readLine());
        int[][] field = new int[N][N];
        for (int i=0; i<N; i++)
            field[i] = Arrays.stream(br.readLine().split(" "))
                        .mapToInt(Integer::parseInt)
                        .toArray();
        for (int height=0; height<=100; height++){
            int area = 0;
            boolean[][] visited = new boolean[N][N];
            for (int i=0; i<N; i++)
                for (int j = 0; j < N; j++) {
                    if (visited[i][j] || field[i][j]<=height) continue;
                    area++;
                    Queue<int[]> Q = new LinkedList<>();
                    Q.add(new int[]{i, j});
                    visited[i][j] = true;
                    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 >= N || ny < 0 || ny >= N) continue;
                            if (visited[ny][nx] || field[ny][nx] <= height) continue;
                            visited[ny][nx] = true;
                            Q.offer(new int[]{ny, nx});
                        }
                    }
                }
            result = Math.max(result, area);
        }
        System.out.print(result);
    }
}