Coding
Determine if a Sudoku board is valid.
Determine if a 9 x 9 Sudoku board is valid. Only the filled cells need to be validated according to standard Sudoku rules: each row, column, and 3x3 sub-box must contain the digits 1-9 without repetition.
Input: board = 9x9 grid where the first row contains 7 twice
Output: FALSE
Explanation: A valid Sudoku cannot contain duplicate numbers in the same row, immediately invalidating the board.
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