Tuesday, September 22, 2009

Sudoku Solver .. by logic



Unable to complete puzzle # 22 in Second-Degree Black Belt Sudoku, I turned to http://www.sudokusolver.co.uk which is able to:
  • use Guess-and-Check soduku solving steps
  • determine whether a sudoku puzzle has a unique solution
Using this website, puzzle #22 is found to have a unique solution, but is not solved using my paper and pencil logic. Naughty!  Do Guess-and-Check style soduku puzzles represent a logical puzzle?  Perhaps yes if you are a computer.

Second-Degree Black Belt Sudoku

I purchased a new sudoku puzzle book, Second-Degree Black Belt Sudoku (by Frank Longo) from a big-box book seller. Why?  Possibly I'm worried that my favorite sudoku puzzle book (New York Post series by Wayne Gould) was nearly full. The good news is that Second-Degree Black Belt Sudoku has:
  • more difficult puzzles compared to the New York Post series by Wayne Gould
  • more puzzles; 300 versus 150

The bad news about Second-Degree Black Belt Sudoku is that:
  • paper quality is not compatible with using an eraser
  • top and bottom margins are smaller leaving less room for margin notes