Dr.Sudoku
SudokuoriginallycalledNumberPlace,isalogic-based,combinatorialnumber-placementpuzzle.Theobjectiveistofilla9×9gridwithdigitssothateachcolumn,eachrow,andeachofthenine3×3sub-gridsthatcomposethegridcontainsallofthedigitsfrom1to9.Thepuzzlesetterprovidesapartiallycompletedgrid,whichforawell-posedpuzzlehasauniquesolution.
CompletedpuzzlesarealwaysatypeofLatinsquarewithanadditionalconstraintonthecontentsofindividualregions.Forexample,thesamesingleintegermaynotappeartwiceinthesamerow,columnorinanyofthenine3×3subregionsofthe9x9playingboard.
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