LeetCode 筆記 - 419. Battleships in a Board

class Solution:
    def countBattleships(self, board: List[List[str]]) -> int:
        
        if not board:
            return 0
        
        length_y = len(board)
        length_x = len(board[0])
        
        count = 0
        for y in range(length_y):
            for x in range(length_x):
                if board[y][x] != 'X':
                    continue

                last_y = y - 1
                last_x = x - 1

                if not (0 <= last_y and board[last_y][x] == 'X') and not (0 <= last_x and board[y][last_x] == 'X'):
                    count += 1

        return count