Puzzle 198 (Akari)

This is a Saturday Akari puzzle.

Puzzle 198

Puzzle 198

I thought this one ended up extremely elegant. The size is just barely large enough for all the logic to work and virtually no piece of information is wasted. Those of you who made it all the way through Puzzle 100, the really large Akari, may have some deja vu in this puzzle. I find this appropriate since Puzzle 200 is coming up so shortly.


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8 Responses to “Puzzle 198 (Akari)”

  1. mathgrant Says:

    Oh, come the **** on. That was just plain evil! Solvable, logical, and neat, yes, but also evil. πŸ™‚

  2. MellowMelon Says:

    You’re complaining about an evil puzzle today? Uh oh…

  3. Georgi Says:

    Evil, insofar as logic required thinking a few steps ahead, which is not so difficult in a puzzle of this size, but I found it unavoidable towards the middle of solving it.
    So… Should we be expecting two puzzles tomorrow, so that Puzzle 200 falls on Sunday? Apparently, you have something very diabolical in store πŸ™‚

  4. MellowMelon Says:

    Whether this puzzle requires thinking ahead or not depends on how loose your definition is. I would argue it only requires careful observation of bulb pairs (7 of them), but they are very interwoven with each other so some solvers may not count it as direct logic.

    As for your question… that would be telling. πŸ˜›

  5. TheSubro Says:

    Great puzzle. Solved it on a plane. Nosy neighbor thought I was a freak to be solving this strange thing with a pen and a pencil.

    Keep these special ones coming … just ensure that they do have solutions that humans can find.



  6. MellowMelon Says:

    I’m quite confident this one is human-solvable. It just requires setting up a bunch of pairs simultaneously.

    Since people seem to be having trouble finding this solution, here’s how this is intended to go:
    — First, set up four simultaneous bulb pairs on the outer columns and rows using two 1s and two 2s. Mark X’s appropriately.
    — Take the 2 on R5. It can have at most one bulb in the UR directions thanks to the 1. The same deduction applies to the 2 on R6 in reverse.
    — Because of that, each 2 on R5 or R6 has at least one bulb near the center of the puzzle… but there can be at most two bulbs total in this section, so it’s actually exactly one for each.
    — This sets up three bulb pairs. The 2 on R5 and the 1 near the top right corner, the 2 on R6 and the 1 near the bottom left corner, and the 2s on R5 and R6. Mark X’s appropriately. (If you can’t see the pairs between the 2 and 1, look harder. I have never seen this kind of pair used except in my puzzle 100, so it’s not an easy find.)
    — After all these X’s are marked, the 2 on R4 has two adjacent X’s and you can finally put down some bulbs. The rest is pretty easy.

    • rob Says:

      I think there’s a slight short-cut you can take here, at least for placing the first bulbs: After your first step above, you can put an X in R5C4 because together with the nearby 2, the 1 near the bottom left would be blocked otherwise. That forces the NW 2 to have the bulbs on the outside.

      Nice puzzle!

      • MellowMelon Says:

        I would consider this the trial and error method of finding the pairs I mentioned in my comment, as the same logic is being exploited. πŸ˜› Not to say your method wouldn’t be easier to find in practice.

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