Puzzle 280 (Yajilin) [Squares]

This is a Yajilin puzzle, with a twist. Black squares are no longer confined to a single cell, but may span any square area of cells. There may be no black rectangles of different side lengths, and no two separate squares may be adjacent. The numbers indicate the total number of black spaces pointed to (not the total amount of distinct black squares). The closed loop behaves as it did in Yajilin.

Puzzle 280

Puzzle 280

(Click for larger size)


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13 Responses to “Puzzle 280 (Yajilin) [Squares]”

  1. Rob Says:

    Interesting variation — from solving this one it feels like it has potential. It was definitely fun to solve.

  2. mathgrant Says:

    An impressive step up from the previous Yajilin Squares. You made the givens symmetrical, you made the logic harsher. . . .

    This one’s a MellowMelon puzzle, all right.

  3. stigant Says:

    Do the numbers indicate how many different black squares are pointed to or how many different black cells are pointed to (some of which may belong to the same black square)?

  4. stigant Says:

    Oops, I can see that it must be the number of cells rather than squares.

  5. aclayton Says:

    Really enjoyed this one, had that patented tight solving path, symmetrical givens..

    I remember how excited I got when first encountering Nikoli Yajilins in their books, and was happy when they were added to the site, but soon found them seeming pretty lacking in terms of opportunity for creative logic tricks. This variation is a welcome breath of fresh air for the type, I think..

    • mathgrant Says:

      While I agree to an extent on wishing Nikoli might use more creative logic in certain puzzles, one thing I’ve learned from my pre-Nikoli experience is that there’s a thin line between difficulty and unrewarding trial and error with a huge search space and no obvious ways to go, and Nikoli does an amazing job at avoiding the latter territory. I’ve done enough computer-generated Slitherlink puzzles to know that a difficult puzzle is not always rewarding just because it’s difficult. I’m no expert or Nikoli insider, but it is quite possible that these ideas play a role.

      • MellowMelon Says:

        My main gripe with nikoli’s Yajilin is that they very rarely draw anywhere close to the “difficulty” territory at all. I know they like to keep their puzzles accessible, but they post some thought-provoking stuff in other types, and I think a few of the puzzles I’ve posted here show it’s possible to push the boundary more than they have. Take this one for instance.

      • mathgrant Says:

        MellowMelon, you definitely have a point there, and I agree that your puzzle 60 pushes the boundary while having a sensitivity to it that keeps it enjoyable. I never claimed that what Nikoli is doing is right or wrong; I merely attempted to explain it.

        I think I’m just the type of solver who is thankful to have puzzles that don’t actually CROSS the boundary, and appreciates the artistry in Nikoli’s puzzles without being too particular. I appreciate a well-crafted difficult Akari, but I also never skip the easy 10×10 ones in any Nikoli publication before I retire it. In fact, out of all the puzzle types on http://www.nikoli.co.jp/en/puzzles/ , the only ones I ever skip, regardless of difficulty, are Numberlink and Sudoku puzzles larger than 9×9.

  6. Tom.C Says:

    Nice – enjoyed this one a lot. Thanks!


  7. GaS Says:

    Hi, I couldn’t undestant the following sentence: “There may be no black rectangles of different side lengths”.
    What *rectangles*? I think that black cells are in squares formation, isn’t it?


    • MellowMelon Says:

      My intent with that sentence was not to allow black cells to make up things like a 1 by 2 rectangle (or 2 by 3 or whatever). If you have any adjacent grid spaces that are black, they have to form an n by n square. Does that help?

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