49 lines
1.8 KiB
Markdown
49 lines
1.8 KiB
Markdown
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Determine if a `9 x 9` Sudoku board is valid. Only the filled cells need to be validated **according to the following rules**:
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1. Each row must contain the digits `1-9` without repetition.
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2. Each column must contain the digits `1-9` without repetition.
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3. Each of the nine `3 x 3` sub-boxes of the grid must contain the digits `1-9` without repetition.
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**Note:**
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* A Sudoku board (partially filled) could be valid but is not necessarily solvable.
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* Only the filled cells need to be validated according to the mentioned rules.
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**Example 1:**
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Input: board =
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[["5","3",".",".","7",".",".",".","."]
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,["6",".",".","1","9","5",".",".","."]
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,[".","9","8",".",".",".",".","6","."]
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,["8",".",".",".","6",".",".",".","3"]
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,["4",".",".","8",".","3",".",".","1"]
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,["7",".",".",".","2",".",".",".","6"]
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,[".","6",".",".",".",".","2","8","."]
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,[".",".",".","4","1","9",".",".","5"]
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,[".",".",".",".","8",".",".","7","9"]]
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Output: true
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**Example 2:**
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Input: board =
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[["8","3",".",".","7",".",".",".","."]
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,["6",".",".","1","9","5",".",".","."]
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,[".","9","8",".",".",".",".","6","."]
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,["8",".",".",".","6",".",".",".","3"]
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,["4",".",".","8",".","3",".",".","1"]
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,["7",".",".",".","2",".",".",".","6"]
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,[".","6",".",".",".",".","2","8","."]
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,[".",".",".","4","1","9",".",".","5"]
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,[".",".",".",".","8",".",".","7","9"]]
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Output: false
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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.
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**Constraints:**
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* `board.length == 9`
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* `board[i].length == 9`
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* `board[i][j]` is a digit `1-9` or `'.'`.
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