def isValidSudoku(board):
    """
    :type board: List[List[str]]
    :rtype: bool
    """
    rows = [set() for x in range(9)]
    columns = [set() for x in range(9)]
    squares = [[set() for x in range(3)] for y in range(3)]
    
    for x in range(9):
        for y in range(9):
            cell_value = board[x][y]
            if cell_value == ".":
                continue
            if cell_value in rows[x] or cell_value in columns[y] or cell_value in squares[x//3][y//3]:
                return False

            rows[x].add(cell_value)
            columns[y].add(cell_value)
            squares[x//3][y//3].add(cell_value)
    
    return True
        

print(isValidSudoku([["5","3",".",".","7",".",".",".","."]
,["6",".",".","1","9","5",".",".","."]
,[".","9","8",".",".",".",".","6","."]
,["8",".",".",".","6",".",".",".","3"]
,["4",".",".","8",".","3",".",".","1"]
,["7",".",".",".","2",".",".",".","6"]
,[".","6",".",".",".",".","2","8","."]
,[".",".",".","4","1","9",".",".","5"]
,[".",".",".",".","8",".",".","7","9"]]))