leetcode第36题：有效的数独

class Solution:
    def isValidSudoku(self, board: List[List[str]]) -> bool:
        rows = [{} for i in range(9)]
        column = [{} for i in range(9)]
        box = [{} for i in range(9)]
        for i in range(9):
            for j in range(9):
                # 读取元素
                nums = board[i][j]
                # 计算3*3方格的下标
                index = (i //3) *3 + j//3
                if nums!=‘.‘:
                    # 字典的get() 如果nums元素没有，则生成并赋值为0，然后对值加1
                    rows[i][nums] = rows[i].get(nums,0)+1
                    column[j][nums] = column[j].get(nums,0)+1
                    box[index][nums] = box[index].get(nums,0)+1
                    if rows[i][nums]>1 or column[j][nums]>1 or box[index][nums]>1:
                        return False
        return True