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arXiv · 2607.05728

Sudoku Grids That Require Many Clues

David Eppstein·Xinyu·Zhang
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Abstract

Motivated by worst-case algorithmic time bounds for solving sudoku, we prove that a majority of filled-in $n^2\times n^2$ sudoku grids require all but a logarithmic fraction of cells to be filled by clues. For $9\times 9$ and $16\times 16$ sudoku, we construct grids that require $18$ clues and $80$ clues.

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David Eppstein, Xinyu, Zhang. 2026-07-07. Sudoku Grids That Require Many Clues. https://arxiv.org/abs/2607.05728

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