Puzzle 120 – Yajilin

This is a Tuesday yajilin puzzle. It uses the GMPuzzles rules that not all grey cells must contain a clue. If you don’t like those rules, just pretend the empty grey cells have 0’s pointing to the edge.

Technically, I’ve posted a variationless yajilin before, but it wasn’t really what most people would call a puzzle, so I’ll still count this as the first.

This might be on the hard side, but it’s the second easiest puzzle in this week I think, although I have been notably bad at estimating difficulty before.


Puzzle 93 – Yajilin [DOMINO]

This is a Tuesday yajilin. However, instead of shaded cells not being adjacent to any other shaded cell, they must be adjacent to exactly one other black cell.

Oops. This was intended to be Tuesday-ish, but definitely came out pretty far on the hard side…


Puzzle 73 – Yajilin [unique clues]

This is a Tuesday yajilin puzzle. To solve it, first you must place apositive integer to the left of each cross and mark one of the four directions of the cross so that no two clues are the same. (e.g. You may have a “1←” clue and a “1↑” clue, but you may not have two “1↑” clues). Then solve the resulting yajilin.

This puzzle may be easier than yesterday’s, but I felt that I should start with a tapa, which has had this variation before. Yajilin is somewhat different than Tapa however, in the sense that even when the solution is known, there are still multiple possibilities for a clue in a given position. Therefore, I will set the standard that only the solution to the Yajilin must be uniquely defined, not necessarily the clues themselves.

Again, it’s worth reiterating that 0 is not a positive integer.


Puzzle 59 – Yajilin [Mastermind]

These are two Monday yajilin puzzles. There are numbers in the center to represent how many squares are shaded in corresponding cells of each row.  For example, a ‘0’ means that there are no black cells in that row that would land in the same place if you overlayed the two puzzles.

The answer to the first meta puzzle was: “EASY”. I hope that everyone solved that, but in case you didn’t, it was found by taking the first letter of each word. This was motivated by the fact that they were separated from the rest of the word with a dash, and pronounced as their own syllable. It was also verified because the puzzle was in fact, easy.


Puzzle 35 – Yajilin and

This is a yajilin puzzle with a little bit of a backstory.  Here is where I told Chaotic I was proving NP-completeness of KenKen, and after complicatedly and inelegantly doing so, here is where he did so in a really simple and  annoying-that-I-didn’t-think-of-it manner. Lastly, “My target: Prove or disprove that Yajilin is NP-complete” – Chaotic_iak.

The following Yajilin has 4 solutions, can you find them all?

So this week was a little bit experimental without the day ratings and exploring an idea rather than a theme, but I had fun making these. Also, note the double meaning in the title. The other puzzles had titles like “Seek-and-Spell and Anglers” where as this one has no second puzzle, yet this is also a Yajilin “and”. (The shaded cells could be filled with numbers pointing toward the edge or with no information, but I was lazy and they are pretty implied so…)

Note that this is not a proof of NP-completeness without crossing wires, which I was not able to manage. I found how to do shifting, turning, and copying wires, but not crossing.