题目：

题解：

class Solution:
    def isValidSudoku(self, board: List[List[str]]) -> bool:
        uni = (defaultdict(set), defaultdict(set), defaultdict(set))
        for i in range(9):
            for j in range(9):
                s = board[i][j]
                if s == '.': continue
                if s in uni[0][i] or s in uni[1][j] or s in uni[2][(i//3)*3 + j//3]: return False
                uni[0][i].add(s)
                uni[1][j].add(s)
                uni[2][(i//3)*3 + j//3].add(s)
        return True