According to Wikipedia, Sudoku is a logic-based, combinatorial number-placement puzzle. In classic sudoku, the objective is to fill a 9×9 grid with digits so that each column, each row, and each of the nine 3×3 subgrids that compose the grid (also called “boxes”, “blocks”, or “regions”) contain all of the digits from 1 to 9.

These are the rules of the regular sudoku:

- Each row must contain every number from 1 to 9 exactly once.
- Each column, similarly, needs one of every number from 1 to 9.
- Each 3x3 ‘region’ needs to follow the same 1–9 pattern.

Knowing what a…

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