leetcode: explore-array-30 有效的数独

class Solution(object):
    def isValidSudoku(self, board):
        """
        :type board: List[List[str]]
        :rtype: bool
        """
        if not board:
            return True

        # 行列同时检查
        line_dict = {}
        col_dict = {}
        # 3*3 检查
        three_dict = {}
        for col in range(len(board[0])):
            for line in range(len(board)):
                cur_num = board[line][col]
                if cur_num == ".":
                    continue

                # 列固定
                if not col_dict.get(col):
                    col_dict[col] = {}
                if col_dict[col].get(cur_num):
                    return False
                col_dict[col][cur_num] = 1

                # 行固定
                if not line_dict.get(line):
                    line_dict[line] = {}
                if line_dict[line].get(cur_num):
                    return False
                line_dict[line][cur_num] = 1

                # 3*3
                three_col = col // 3
                three_line = line // 3
                if not three_dict.get(three_col):
                    three_dict[three_col] = {}
                if not three_dict[three_col].get(three_line):
                    three_dict[three_col][three_line] = {}
                if three_dict[three_col][three_line].get(cur_num):
                    return False
                three_dict[three_col][three_line][cur_num] = 1

        return True