October 15, 2010

Friday Puzzles #74


As much as I’d like to go on about a rocking American band of the 70’s, I think I’d better Keep It Simple, Stupid. Especially in light of recent puzzle-writing dickhead errors on my part. So what could be more simple than a 10×10 Akari?

Well: I haven’t posted the rules before (competent use of the mouse in a leftward direction should help you here); and 10×10 Akari are usually lame. This one isn’t. Enjoy!

#091 Akari – rated medium

All puzzles © Tom Collyer 2009-10

- 10 comments by 1 or more people Not publicly viewable

[Skip to the latest comment]
  1. Jonah

    Nice puzzle. That’s quite the subtle break-in.

    15 Oct 2010, 02:31

  2. MellowMelon

    Oh man, multiple bulb pairs. You know that’s my favorite kind of step.

    15 Oct 2010, 15:54

  3. There are only so many ways that a 10×10 akari can be non-lame – you can try stuff with a slightly denser packing of the grid with black squares, but generally you need more room than 10×10 normally allows you. Anyway, hopefully it provides fun for those solvers who haven’t seen lots of akari.

    It’s a shame there are only two orthogonal directions on paper/screen to play around with bulb pairs. After you do something like the botsu baku nikoli.com puzzle by juno there doesn’t seem to be many obvious choices as to where else you might push the boundaries of the logic. Although again the later Guten puzzle in the Botsu Baku is very good too.

    15 Oct 2010, 18:31

  4. mathgrant

    By nikoli’s standards, this is a Hard or an Extra.

    Also, I concur with what MellowMelon said.

    17 Oct 2010, 18:17

  5. mathgrant

    Please note: the link to the Akari rules on your blog’s sidebar is broken.

    17 Oct 2010, 20:59

  6. Ta – it’s fixed now :)

    17 Oct 2010, 22:59

  7. Marcin Mucha

    Nice puzzle! I wouldn’t go as far as calling it a Nikoli Extra kind of hard, but I really enjoyed the initial break-in, quite unusual.

    Not sure if it’s a good place to ask this question, but would you guys mind discussing the mechanics of solving akari on paper?
    I have no trouble with most puzzles, but being used to nikoli’s application makes it sort of hard for me to solve akaris this way. See, the trouble is
    that I feel like I need 3 kinds of marks: (a) bulbs (b) non-bulbs (c) lighted space. Very often (b) = (c) but obviously it’s not always the case. I am
    using circles for (a) and slashes (”/”) for (b) and I’m keeping track of (c) in my head. This is because I am using this circle/slash combo in most
    geometric puzzles (nurikabe, tapa, battleships, coral, etc.) and I can do it relatively fast. If I’m adding another symbol, it makes speed solving harder
    because it’s harder to distinguish between a larger number of symbols (also the marking itself becomes harder). On the other hand, I sometimes
    don’t see (c) correctly and that can lead to some ugly misreads. What system are you using?


    18 Oct 2010, 10:45

  8. Marcin, my paper notation is as follows. Where there definitely can’t be a bulb (e.g. R2C3), I put a small dot. Where there is a bulb, I draw in a big blob, and then I draw straight lines up/down and left/right through all the squares it is possible to do. These lines then act as notation for the lighted space. If you are really trying to solve quickly, sometimes it isn’t necessary to draw all these lines in (for example, when you would only be highlighting squares already lit up).

    I haven’t had any misunderstandings since I started using this notation. Thanks for the comment!

    18 Oct 2010, 14:07

  9. Ronald

    I really enjoyed this, thanks! Didn’t think it was that hard – once the breakin was established, the rest of the puzzle fell pretty hard: I’ve definitely seen a lot harder (tho maybe not 10×10)

    18 Oct 2010, 17:01

  10. Taking into account all the the comments and making an average, the wisdom of crowds probably agrees this was a medium ;)

    18 Oct 2010, 23:55

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Welcome to the blog of current UKPA sudoku champion, two-time Times national sudoku champion and general logic puzzle fan Tom Collyer.

Home of the original Friday Puzzles, each Friday I publish a 100% original and handmade logic puzzle, inspired by the world-famous Nikoli company.

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