Thursday, 3 June 2010

Friday Puzzles #54

Again, I find myself in two minds as to how this puzzle ought to be classified. You see, the problem is most Hashi that I do are fairly generic, and probably require a solving set of about five moves applied with various degrees of imagination. With this Hashi, there are two polarised solving experiences that I can envisage you, dearest reader, having. Either something clicks, and everything gets pretty standard pretty quickly, or else you’ll struggle a little bit and the solve will turn into something of a slog.

It seems to me that the best case scenario for me as the author is that everyone manages to click. In which case there seems to be only a minor pay-off before everything gets standard. Still, having steadfastly argued earlier this week that an otherwise unspectacular puzzle still had some merit to it based on a novel and interesting move to finish it off, I suppose I should be happy with this. Enjoy!

Update: My thanks to Bryce Herd who pointed out that an earlier version of this puzzle failed to satisfy a basic theorem of graph theory!
    #064 Hashiwokakero – rated hard
All puzzles © Tom Collyer 2009-10


  1. Sure enough, there was a very satisfying a-ha moment where the puzzle went from “omg how is this possibly going to be unique?” to fairly smooth sailing. I like the fact (not to spoil too much) that it’s a Hashi where the center is more important/useful than the edges/corners to getting going, and where once you see the logic it feels like its been hidden in plain sight all along.

  2. I’m having a problem. I think there’s a parity issue; I count five rows where the sum of the clues is odd.

  3. That’s a really interesting point that you raise, and a nice exercise in graph theory. I think that’s a silly mistake resulting from my trying to disguise the clues, and one that I can only assume I missed is because it only becomes apparent once you have connected up all the components, and assume that you are done!

    Anyhow, it’s fixed now!


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