Sudoku is a logic-based number-placement puzzle. 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”) contains all of the digits from 1 to 9.
Checking a Sudoku puzzle is the process of verifying whether the puzzle has been solved correctly. This can be done by checking that each row, column, and 3×3 subgrid contains all of the digits from 1 to 9, and that no digit is repeated within any row, column, or 3×3 subgrid.
