[JAVA] 2468번 안전 영역

문제

https://www.acmicpc.net/problem/2468

2468번: 안전 영역

풀이

 

 

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.StringTokenizer;

public class 안전영역 {
	static int arr[][];
	static boolean visited[][];
	static int N;
	static int dx[] = {-1, 1, 0, 0};
	static int dy[] = {0, 0, -1, 1};
	static int result[];
	
	public static void dfs(int y, int x, int depth) {
		visited[y][x] = true;
		
		for (int i = 0; i < 4; i++) {
			int xx = x + dx[i];
			int yy = y + dy[i];
			
			if (xx < 0 || xx >= N || yy < 0 || yy >= N) continue;
			if (arr[yy][xx] > depth && !visited[yy][xx]) {
				dfs(yy, xx, depth);
			}
		}
	}
	
	public static void main(String[] args) throws NumberFormatException, IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		StringTokenizer st;
		
		N = Integer.parseInt(br.readLine());
		arr = new int[N][N];
		int max_len = 0;
		
		for (int i = 0; i < arr.length; i++) {
			st = new StringTokenizer(br.readLine());
			for (int j = 0; j < arr.length; j++) {
				arr[i][j] = Integer.parseInt(st.nextToken());
				if (max_len < arr[i][j]) max_len = arr[i][j];
			}
		}
		
		result = new int[max_len];
		
		for (int k = 0; k <= max_len; k++) {
			visited = new boolean[N][N];
			for (int i = 0; i < arr.length; i++) {
				for (int j = 0; j < arr.length; j++) {
					if (arr[i][j] > k && !visited[i][j]) {
						result[k]++;
						dfs(i, j, k);
					}
				}
			}
		} 
		
		int answer = 0;
		for (int i = 0; i < result.length; i++) {
			if (answer < result[i]) answer = result[i];
		}
		
		System.out.println(answer);
		br.close();
	}
}