Puzzle 278 (Numberlink)

This is a Numberlink puzzle.

Puzzle 278

Puzzle 278

(Click for larger size)

I will confess that I am not 100% sure of uniqueness on this puzzle. But be assured that the method I used to convince myself was not “try for awhile to find a different solution”. I did try with success to work out a proof. I’m just not as sure of each step as I would be for proving an ordinary puzzle’s uniqueness.

In my opinion this puzzle is a bit on the easy side for Numberlinks of this size, which means it’s still hard.


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5 Responses to “Puzzle 278 (Numberlink)”

  1. Val Says:

    That was fun! I was glad my instincts were correct because with Numberlinks, if they aren’t, I generally give up without trying again. But when I’m lucky and my intuition serves, it can be really satisfying to solve a good Numberlink. Thanks for the puzzle!

  2. Tom.C Says:

    Nice puzzle, not as brutally tough as some of your other puzzles, but it certainly had some meat on the bones.

    The solution I came across was obtained by using lots of uniqueness strategies; however briefly analysing the structure of this solution tells me that firstly there is no unnecessary wrapping of lines, and secondly the density of the clues in the top-left/bottom-right does effectively force a lot of paths. I’m confident this is a unique solution.

  3. aclayton Says:

    Fun puzzle, I started with the 20’s and it fell into place from there..

    I’m always amazed to see Numberlinks with symmetric givens. I think this type must be one of the most difficult to construct in the first place, and then adding an additional (unnecessary, yet stylistic) constraint.. I wonder what your motivation was – as an extra challenge, for aesthetics? Did keeping symmetry change the construction process between this one and, say, 260?

    • MellowMelon Says:

      It changed a lot. 260 began from a specific idea (which I think is pretty transparent), and proving uniqueness was easy thanks to it. This one mostly was as a challenge to myself to try to pull it off; the original ideas I had for it all got sacrificed for symmetry, but the end result I deemed okay to publish (obviously). I certainly still have work to do, since a lot of the large nikoli Numberlinks make symmetric *patterns*. God knows how.

  4. linked_puffbird Says:

    Thanks! This was a fun puzzle.

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