529.cpp

class Solution {
public:
    vector<vector<bool>> visited;
    int n, m;
    vector<vector<char>> updateBoard(vector<vector<char>>& board, vector<int>& click) {
        int x, y;
        n = board.size();
        m = board[0].size();
        visited.assign(n, vector<bool>(m, false));
        
        for(int i = 0; i < click.size(); i+=2) {
            x = click[i];
            y = click[i + 1];
            dfs(board, x, y);
        }
        return board;
    }
    
    void dfs(vector<vector<char>>& board, int x, int y) {
        if (board[x][y] == 'M') {
            board[x][y] = 'X';
            return;
        }
        if (board[x][y] != 'E') {
            return;
        }
        int offsetX[8] = {-1, -1, -1, 0, 0, 1, 1, 1};
        int offsetY[8] = {-1, 0, 1, -1, 1, -1, 0, 1};
        int mines = 0;
        
        visited[x][y] = true;
        for(int i = 0; i < 8; i++) {
            int row = x + offsetX[i];
            int col = y + offsetY[i];
            if (row < 0 || row >= n || col < 0 || col >= m)
                continue;
            if (board[row][col] == 'M')
                mines++;
        }
        if (mines > 0) {
            board[x][y] = '0' + mines;
        } else {
            board[x][y] = 'B';
            for(int i = 0; i < 8; i++) {
                int row = x + offsetX[i];
                int col = y + offsetY[i];
                if (row < 0 || row >= n || col < 0 || col >= m) continue;
                dfs(board, row, col);
            }
        }
    }
};