该数独可能只填充了部分数字，其中缺少的数字用 . 表示。
class Solution:
# @param board, a 9×9 2D array
# @return a boolean
def isValidSudoku(self, board):
rows = [list(lst[::]) for lst in board]
columns = [[lst[idx] for lst in board] for idx in range(9)]
blocks_origin = [board[row][column] for x in [[0, 1, 2], [3, 4, 5], [6, 7, 8]] for y in [[0, 1, 2], [3, 4, 5], [6, 7, 8]] for row in x for column in y] # 利用一些技巧直接按块储存
数据
blocks = [[blocks_origin[row * 9 + column] for column in range(9)] for row in range(9)]
check = lambda lst: all([lst.count(x) == 1 for x in lst if x != ‘.’]) # 判断一条记录（按某种方式排列的九个数字）是否合法
return all([check(x) for style in (rows, columns, blocks) for x in style]) # 一步搞定
