Friday, 22 October 2010

Friday Puzzles #75

A.K.A. Tom Collyer finishes unfinished business

A.K.A. Tom Collyer keeps his promises (at least sometimes, at any rate haha…)

A.K.A. Who needs a list of pentominos by the side of a puzzle anyway?

So this is a tough cookie. But it’s worth it, I promise you. 75% solves beautifully well, and the last quarter is a bit of a head scratch. If it’s too much of a head scratch, you can probably trust my good nature and use a few hinted shortcuts to finish the puzzle. Enjoy!
    #092 Nurikabe – rated hard
P.S. A few weeks back I eulogised about how great my Marathon puzzles for the LMI test were. As it turned out, the test was somewhat of a disaster, with a high proportion of broken puzzles and plenty of egg on my face. That said, there were still some rather good puzzles and you can probably expect to see a couple of them reposted on my blog on weeks when I’ve not got a spare mo to do a semi-decent puzzle.

Anyhow, the Heyawake was actually broken – which made me die more than a little inside because if you skipped over the contradiction the mistake implied, it was in my opinion the best of the three puzzles. I did fix it, but it’s not the same :(.
    #093 Kakuro – rated hard

    #094 Masyu – rated hard

    #095 Heyawake – rated hard
All puzzles © Tom Collyer 2009-10

3 comments:

  1. Awesome on the Nurikabe, even getting that U in somewhat cleanly. The last part could be solved by a visualization of the consequences of extending the 5-that-is-the-W to the right. Not very direct, but seeing the resulting trapped black cells is quick and easy.

    It was hard not to fall back into Shape Nurikabe mode from motris’s test and automatically stop 5s from becoming pentominoes I had already put down.

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  2. Without wanting to give away too many spoilers, I think the slightly more direct way I had in mind was finding an area of the grid where the T is forced.

    With regards to forcing the U – the only two ways I could see how to do it were either as I did it (which I thought was the simpler option), or to have a 2×3 box with a complete black square border. Anything else that might have worked seemed to do so non-uniquely. Actually, with the way I did things it was quite handy to note that if you want to force a path, there are a few pentomino pairs/triplets that seem to live pretty nicely close to each other…

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  3. Nurikabe is awesome, I solved almost all your Nurikabe puzzles and I liked each one of them, but this one became my favorite of your blog. Even though it is rated hard after seeing twelve 5's I convinced myself that it has to be 12 pentomino's :), after that its very easy.
    I wanted to comment on this long back on your previous blog, but it was locked for other to comment.

    Regards,
    Ravi

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