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16-Clue Sudoku
The Sudoku with no unique solution
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Nur 16 Hinweise, also keine eindeutige Lösung — füllen Sie jede Zelle regelkonform aus; jede gültige Füllung gilt als gelöst.
A uniquely-solvable Sudoku needs at least 17 clues, so 16 always has many solutions — any rule-valid filling clears it. The in-game UI is in Japanese.
Puzzle meets YouTube
All videos →Videos behind this puzzle and the ideas around it.
Why Sudoku can't go below 17 clues — a 7-million-hour supercomputer proof
The minimum number of clues a uniquely-solvable Sudoku can have is 17 — and proving it took a supercomputer about 7 million hours. The story behind our 16-clue Sudoku, which can never have a unique solution.
