The Sudoku Blog

The ideas behind the game — how a solver generates a puzzle that has exactly one answer, and the human logic techniques that the AI Hint engine uses to solve it.

Inside the AI

How a Sudoku Solver Works: Backtracking and Unique Solutions

Depth-first search, constraint checking, and the clever uniqueness test that guarantees every generated puzzle has exactly one solution — so you never have to guess.

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Strategy

The Logic Techniques Behind Every Sudoku

From naked and hidden singles up to pairs, pointing pairs and the X-Wing — the deductions that turn a wall of empty cells into a fully solved grid.

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