[백준] 2468 안전 영역 - Brute Force / Java

• 문제 링크

2468번: 안전 영역

 

• 풀이 과정

 

• 풀이 코드

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

public class Main {

    static int n;
    static int[][] map;
    static boolean[][] visit;
    static int[] dy = {-1, 1, 0, 0};
    static int[] dx = {0, 0, -1, 1};

    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
        StringTokenizer st;

        n = Integer.parseInt(br.readLine());
        map = 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++) {
                int h = Integer.parseInt(st.nextToken());
                map[i][j] = h;
                if (h > max)
                    max = h;
            }
        }

        int res = 0;
        for (int h = 0; h <= max; h++) {
            visit = new boolean[n][n];
            int cnt = 0;

            for (int i = 0; i < n; i++) {
                for (int j = 0; j < n; j++) {
                    if (!visit[i][j] && map[i][j] > h) {
                        dfs(i, j, h);
                        cnt++;
                    }
                }
            }
            res = Math.max(res, cnt);
        }

        bw.write(String.valueOf(res));
        bw.flush();
    }

    private static void dfs(int y, int x, int h) {
        visit[y][x] = true;

        for (int i = 0; i < 4; i++) {
            int ny = y + dy[i];
            int nx = x + dx[i];

            if (ny < 0 || ny >= n || nx < 0 || nx >= n)
                continue;
            if (!visit[ny][nx] && map[ny][nx] > h)
                dfs(ny, nx, h);
        }
    }

}