Friday 4 March 2011

Friday Puzzles #94

Don’t Masyu look so much better with a nice bit of symmetry!? This week’s puzzle would probably count as a medium if it were 10×10 rather than 18×10 – but perhaps that’s only because I don’t believe you can have a hard 10×10 Masyu. I’d say it’s definitely hard by standards. Included in this puzzle is a twist on an old chestnut, which nevertheless I haven’t seen before. Maybe I’ll send it to 11 some other time. Still, I reckon this puzzle isn’t so bad either. Enjoy!
    #120 Masyu – rated medium
All puzzles © Tom Collyer 2009-11


  1. I wouldn’t say it was hard (maybe on the border). I’ve only done a handful of Masyus, mainly thanks to your blog for me getting into them and understanding them better, and I found it pretty straightforward with only one or two points where I had to stop and think for a few seconds.

    Nevertheless, I found it a very smooth puzzle and, once again, excellently constructed.

  2. Without wanting to give the game away too much, I can’t see where the left solve of the puzzle can be resolved by anything other than noticing the trick I was going on about, and that’s certainly non-trivial. Although I do agree that forcing symmetry onto a puzzle does mean that it is quite easy in places simply to force the solution to be unique!

  3. I did make an assumption that the solution was unique which helped me speed though. And I’m sorry to say that I didn’t notice your trick – although that’s probably more to do with me not doing Masyus often.

    Maybe you can write a book on them akin to Thomas Snyder’s wonderful TomTom book which I’m currently working my way through and is thoroughly delightful :)

  4. Ah fair enough. As the author, I’m afraid I have to disregard any uniqueness strategies (or else how do you know it solves uniquely in the first place ;) ), and this is taken into account with my ratings…

  5. If your trick has nothing to do with the themed step in this one (, then I missed it too.

  6. MellowMelon: yes I think it does – or at least something equivalent – assuming you referring to doing things to avoid a loose strand being trapped in a cul-de-sac. Although there are plenty of goodies in that puzzle! What I am referring to is a specific configuration of four circles which forces a couple of deductions.

    Actually, to reply to email correspondent Jeffrey H and presumably to lots of other readers you could by-pass this configuration with a little bit of “painting”, as was pointed out to me in this email. I think what I’ll have to do is send it to 11 to make sure everyone gets the point next week!

  7. Thanks for your reply. Enjoyed the puzzle, and looking forward to the follow-up :)


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