dfs: POJ 2386 JAVA

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        int N = scan.nextInt();
        int M = scan.nextInt();
        char[][] field = new char[N][M];
        int res = 0;
        for (int i = 0; i < N; i++) {
            for (int j = 0; j < M; j++) {
                field[i][j] = scan.next().charAt(0);
            }
        }

        for (int i = 0; i < N; i++) {
            for (int j = 0; j < M; j++) {
                if (field[i][j] == 'W') {
                    dfs(i, j, field);
                    res++;
                }
            }
        }
        System.out.println(res);
    }

    public static void dfs(int x, int y, char[][] field) {
        field[x][y] = '.';
        for (int k = -1; k <= 1; k++) {
            for (int l = -1; l <= 1; l++) {
                int dx = x + k;
                int dy = y + l;
                if (dx >= 0 && dx < field.length && dy >= 0 && dy < field[0].length && field[dx][dy] == 'W') {
                    dfs(dx, dy, field);
                }
            }
        }
    }

}