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:
-
Each row must contain the digits
1-9without repetition. -
Each column must contain the digits
1-9without repetition. -
Each of the nine
3 x 3sub-boxes of the grid must contain the digits1-9without 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.
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
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 == 9board[i].length == 9board[i][j]is a digit1-9or'.'.
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