[8.20]leetcode 每日一题，

class Solution {
    int[] xG = {0, 1, -1, 0, 1, -1, -1, 1};
    int[] yG = {1, 0, 0, -1, 1, -1, 1, -1};
    public char[][] updateBoard(char[][] board, int[] click) {
        int x = click[0];
        int y = click[1];
        if (board[x][y] == 'M') {
            board[x][y] = 'X';
            return board;
        } else {
            dfs(board, x, y);
        }
        return board;
    }
    public void dfs(char[][] board, int x, int y) {
        int count = 0;
        for (int i = 0; i < 8; i++) {
            int tx = x + xG[i];
            int ty = y + yG[i];
            if (tx >= 0 && tx < board.length && ty >= 0 && ty < board[0].length &&board[tx][ty] == 'M') {
                    count++;
            }
        }
        if (count > 0) {
            board[x][y] = (char) (count + '0');
        } else {
            board[x][y] = 'B';
            for (int i = 0; i < 8; i++) {
                int tx = x + xG[i];
                int ty = y + yG[i];
                if (tx >= 0 && tx < board.length && ty >= 0 && ty < board[0].length) {
                    if (board[tx][ty] == 'E') {
                        dfs(board, tx, ty);
                    }
                }
            }
        }
    }
}