Friday 1 March 2013

Friday Puzzles #198

You should know the drill by now.  This week another classic puzzle, which kind of defies a sensible rating.  I have good reasons to equally call this easy, medium or hard.  You'll hopefully see what I mean after you've solved this, dearest reader. Enjoy!

Week 7:
Saturday (Scattered, Bram)
Sunday (Multiplication Table, Seungjae)

Week 8:
Monday (Killer Pair, Fred)
Tuesday (Point To Next, Prasanna)
Wednesday (Greater Than Killer, Bastien)
Thursday (Non Consecutive-Anti Knight, Rishi)
    #235 Sudoku – rated medium
All puzzles © Tom Collyer 2009-13.


  1. Hi Tom! Nice sudoku.9 mins 16 s.
    I utilised something called a simple colouring at the end which utilises a bulb logic and gives ON and OFF status to numbers.The same was confirmed when i tried from the stuck point using the sudoku solver by Andrew stuart.Does this sudoku indeed contains a simple colouring or it can be solved in a different way say a swordfish or something?!
    How do top solvers like you proceed from this point?!Using the same simple colouring strategy or something else?!
    Thks in advance :)

    1. Yes, the colouring trick was exactly what I intended. I had thought it was reasonably difficult to spot - I had good fun explaining how it worked to people in my office yesterday - but several (albeit fairly impressive!) solvers managed to get this out in 3-4 minutes, according to the facebook group leaderboard.

      So yeah easy, in that modulo that step the puzzle was quite simple, and given you only needed to use it at the end of the puzzle a simple bifurcation would also solve things quite quickly. Hard, because I believe that colouring is an advanced solving technique that few people are able to spot very quickly. But I plumped with medium, because what else can I call something that I'm not quite convinced is either hard or easy!?

      Thanks for the comment!

  2. Really hope that you get all the time to construct some beautiful puzzles like this.Keep up the good work!

  3. Nice puzzle. I'm not an expert or anything. Solved it in 16 minutes for Sodoku. Can't wait for more!


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