36. 有效的数独

判断一个 9x9 的数独是否有效。只需要根据以下规则，验证已经填入的数字是否有效即可。

数字 1-9 在每一行只能出现一次。
数字 1-9 在每一列只能出现一次。
数字 1-9 在每一个以粗实线分隔的 3x3 宫内只能出现一次。

上图是一个部分填充的有效的数独。

数独部分空格内已填入了数字，空白格用 '.' 表示。

示例 1:

输入:
[
["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"]
]
输出: true
示例 2:

输入:
[
  ["8","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"]
]
输出: false
解释: 除了第一行的第一个数字从 5 改为 8 以外，空格内其他数字均与 示例1 相同。
但由于位于左上角的 3x3 宫内有两个 8 存在, 因此这个数独是无效的。
说明:

一个有效的数独（部分已被填充）不一定是可解的。
只需要根据以上规则，验证已经填入的数字是否有效即可。
给定数独序列只包含数字 1-9 和字符 '.' 。
给定数独永远是 9x9 形式的。

来源：力扣（LeetCode）
链接：https://leetcode-cn.com/problems/valid-sudoku
著作权归领扣网络所有。商业转载请联系官方授权，非商业转载请注明出处。

好水的中等题。。。就en暴

import collections
class Solution:
    def isValidSudoku(self, board: List[List[str]]) -> bool:
        for i in board:
            cnt=Counter(i)
            for c in cnt:
                if cnt[c]>1 and c!='.':
                    return False
        for i in zip(*board):
            i=list(i)
            cnt=Counter(i)
            for c in cnt:
                if cnt[c]>1 and c!='.':
                    return False
        
        def valid(board,a,b):
            s=''
            for i in range(a,a+3):
                for j in range(b,b+3):
                    s+=board[i][j]
            cnt=Counter(s)
            for c in cnt:
                if cnt[c]>1 and c!='.':
                    return False
            return True


        for i in range(0,9,3):
            for j in range(0,9,3):
                if not valid(board,i,j):
                    return False
        return True
        

class Solution:
    def isValidSudoku(self, board) -> bool:
        board9 = []
        for i in range(9):
            for j in range(9):
                if board[i][j] != '.':
                    if board[i][j] not in board9:
                        board9.append(board[i][j])
                    else:
                        return False
            board9 = []

        for i in range(9):
            for j in range(9):
                if board[j][i] != '.':
                    if board[j][i] not in board9:
                        board9.append(board[j][i])
                    else:
                        return False
            board9 = []

        for i in [0,3,6]:
            for j in [0,3,6]:
                for m in range(i,i+3):
                    for n in range(j,j+3):
                        if board[m][n] != '.':
                            if board[m][n] not in board9:
                                board9.append(board[m][n])
                            else:
                                return  False
                board9 = []
        return True