Day033 - 36. Valid Sudoku

36. Valid Sudoku

Determine if a 9 x 9 Sudoku board is valid. Only the filled cells need to be validated according to the following rules:

1. Each row must contain the digits 1-9 without repetition.
2. Each column must contain the digits 1-9 without repetition.
3. Each of the nine 3 x 3 sub-boxes of the grid must contain the digits 1-9 without repetition.

Note:

• A Sudoku board (partially filled) could be valid but is not necessarily solvable.
• Only the filled cells need to be validated according to the mentioned rules.

Example 1:

Input: board = 
[["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"]]
Output: true

Example 2:

Input: board = 
[["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"]]
Output: false
Explanation: Same as Example 1, except with the 5 in the top left corner being modified to 8. Since there are two 8's in the top left 3x3 sub-box, it is invalid.

Constraints:

• board.length == 9
• board[i].length == 9
• board[i][j] is a digit 1-9 or '.'.

내 풀이

from collections import Counter

class Solution:
    def isValidSudoku(self, board: List[List[str]]) -> bool:
        for i in range(9):
            check_row = Counter(board[i])
            check_col = Counter([board[j][i] for j in range(9)])
            
            del check_row["."]
            del check_col["."]

            bool_row = sum(check_row.values()) == len(check_row)
            bool_col = sum(check_col.values()) == len(check_col)
            
            if not bool_row or not bool_col:
                return False

        """
        0,1,2 / 3,4,5 /6,7,8
        """
        ## 1. python의 기본 list 사용
        for row in range(0, 9, 3):
            check_row = board[row:row+3]
            for col in range(0, 9, 3) :
                check_cube = Counter(sum([i[col:col+3] for i in check_row], []))
                del check_cube["."]
                if len(check_cube) != sum(check_cube.values()):
                    return False

        ## 2. numpy의 array 사용
        import numpy as np
        board = np.array(board)
        for row in range(0, 9, 3):
            for col in range(0, 9, 3) :
                check_cube = Counter(sum(board[row:row+3, col:col+3].tolist(), []))
                del check_cube["."]
                if len(check_cube) != sum(check_cube.values()):
                    return False

        return True

# Time Complexity : \(O(N)\)