In a sudoku puzzle, what is the absolute minimum number of clues that must be given to specify a layout with a unique solution? Is one in each row, column, and box (9 total) necessary or sufficient?
1 Answer
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For a standard 9×9 Sudoku, the minimum is 17 squares. It had long been known that at least 16 were required and that 17 was sufficient. This article closes the gap.