419. Battleships in a Board

class Solution {
public:
    int countBattleships(vector<vector<char>>& board) {
        int res = 0;
        for (int i = 0; i < board.size(); i++)
            for (int j = 0; j < board[i].size(); j++) {
                if (board[i][j] == '.' ||
                    i > 0 && board[i-1][j] == 'X' || 
                    j > 0 && board[i][j-1] == 'X')
                    continue;
                res++;
            }
        return res;
    }
};