[백준] 안전영역 2468 - JAVA

문제

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

2468번: 안전 영역

 

풀이

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

public class Main {

	static int n;
	static int arr[][];
	static int result = 0;
	static int dx [] = {1,0,-1,0};
	static int dy [] = {0,-1,0,1};
	
	public static void main (String[] args) throws java.lang.Exception {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		StringTokenizer st;
		
		n = Integer.parseInt(br.readLine());
		
		arr = new int[n][n];
		
		int max = 0;
		
		for(int i=0;i<n;i++) {
			st = new StringTokenizer(br.readLine());
			for(int j=0;j<n;j++) {
				arr[i][j] = Integer.parseInt(st.nextToken());
				max = Math.max(arr[i][j], max);
			}
		}
		
		
		for(int i=0;i<max;i++) {
			bfs(i);
		}
		
		System.out.print(result);
	}		
	
	static void bfs(int depth) {
		Queue<int []> que = new LinkedList<>();
		 boolean visit[][] = new boolean [n][n];
		
		int count = 0;
		for(int i=0;i<n;i++) {
			for(int j=0;j<n;j++) {
				if(arr[i][j] <= depth || visit[i][j]) continue;
				
				count++;
				que.add(new int[] {i, j});
				visit[i][j] = true;
				
				while(!que.isEmpty()) {
					int [] cur = que.poll();
					
					for(int k=0;k<4;k++) {
						int nx = cur[0] + dx[k];
						int ny = cur[1] + dy[k];
						
						if(nx < 0 || ny < 0 || nx >= n || ny >= n) continue;
						if(arr[nx][ny] <= depth || visit[nx][ny]) continue;
						
						que.add(new int[] {nx, ny});
						visit[nx][ny] = true;
					}
					
				}
			}
		}
		result = Math.max(result, count);
	}
}