26.扫雷一次点击

class Solution {
    int dx[8]={0, 0, -1,1,1, 1,-1,-1};
    int dy[8]={1, -1, 0,0,1,-1,-1, 1};
public:
    void dfs(vector<vector<char>>& board, int i,int j){
        if(board[i][j]!='E')return;
        int cnt=0;
        for(int k=0;k<8;k++){
            if(i+dx[k]<0||i+dx[k]>=board.size()||j+dy[k]<0||j+dy[k]>=board[0].size())continue;
            if(board[i+dx[k]][j+dy[k]]=='M')cnt++;
        }
        if(cnt==0){//周围没有雷
            board[i][j]='B';
            for(int k=0;k<8;k++){
                if(i+dx[k]<0||i+dx[k]>=board.size()||j+dy[k]<0||j+dy[k]>=board[0].size())continue;
                dfs(board,i+dx[k],j+dy[k]);
            }
        }
        else{
            board[i][j]=cnt+'0';return;
        }
        return;
    }
    vector<vector<char>> updateBoard(vector<vector<char>>& board, vector<int>& click) {
        int m=click[0],n=click[1];
        if(board[m][n]=='M'){board[m][n]='X';return board;}
        dfs(board,m,n);
        return board;
    }
};