Logic Masters Deutschland e.V.

Chaos Deconstruction #3: Double Snake (11x9)

(Published on 25. July 2022, 03:25 by KNT)

"Hmm..." the evil setter ponders, "how do I DOS the solver's brain?"

"Oh I know! A deconstruction with overlapping regions!"

Many thanks to Vebby and Niverio for testing.

Rules:

Place the digits 1-9 in the grid such that digits do not repeat in any row, column, or region. Regions are 9 cells large, and contain the digits 1-9 once each, but their shapes and locations must be determined. Not every cell in the grid must contain a digit, but every clued cell must.

Within the grid there are two snakes, Snake A and Snake B (one cell wide orthogonally connected paths that do not branch or touch themselves, even diagonally). A digit in a circle indicates the number of surrounding cells in the 3x3 area centered at that cell that are part of Snake A, likewise with squares and Snake B. The snakes may touch each other freely, and may intersect. If two snakes intersect (i.e. they both have a cell in common), they must "cross". More formally, no two adjacent cells in the grid may belong to both Snake A and Snake B. Snakes may intersect at corners, or even at their heads or tails. All is fair play.

Every region is either entirely part of Snake A, or entirely part of Snake B. Cells that exist at intersections of Snake A and Snake B belong to two regions simultaneously.

Implications:

A consequence of these rules is that every cell with a circle, square, or given digit must belong to at least one of the two snakes. A second consequence is that because digits may not repeat in rows or columns, at least two cells in every column must not belong to either snake. These are two important insights necessary to make progress in the puzzle.

Examples:

Below is an example image as to how the snake rules may work. Yellow here is Snake A, blue is snake B, and green are intersections between A and B. Below shows several different ways the snakes could intersect with each other: at their heads or tails (marked by h and t, but may be interchangeable as orientation of the snakes do not matter), at corners, or pass through each other like an X. This example image does not show anything related to regions, though.

οὐροβόρος:

And below is an image of the puzzle. The screenshot of the puzzle below is a Penpa+ screenshot, in which diamonds represent a square and a circle in the same cell. In the CTC link, these diamonds are not there.

CTC link

Penpa+ link

Solution code: Row 9 followed by Column 8, ignoring empty cells.


Solved by Vebby, RJBlarmo, Niverio, SirWoezel, PixelPlucker, JayForty, henrypijames, polar, the_cogito, Jesper, Koalagator2, marcmees, Siebuhh, ancarro, jkuo7, amarins, hepcecob, wenchang, harrison, PippoForte, cdwg2000, ma3n, Mody, Sewerin, Jaych, ONeill, Piatato, lerroyy, Feadoor, Saskia, Tom-dz, ibag, h5663454, Nick Smirnov
Full list

Comments

on 26. August 2023, 20:59 by ibag
Smart construction, loved it!

on 23. February 2023, 15:43 by Piatato
Brilliantly constructed! Really good flow throughout!

on 12. February 2023, 14:10 by ONeill
Wow what a puzzle! Seems monstrous at first but begins to flow very nicely :)

on 28. July 2022, 18:52 by wenchang
Very hard!
https://youtu.be/SPm5HH-fMoA

on 28. July 2022, 05:44 by harrison
What a beautiful dark twisted fantasy that was!

on 25. July 2022, 22:23 by marcmees
an other masterpiece. thanks.

on 25. July 2022, 18:26 by Jesper
Thanks KNT, that was both really weird and cool. Always nice to wrap your head around something quite different!

on 25. July 2022, 18:00 by henrypijames
Don't be scared, people! This in only 4/5 difficulty - AKA a paper tiger. :D

on 25. July 2022, 17:21 by polar
Another brilliant construction! Thanks KNT :)

on 25. July 2022, 16:12 by JayForty
Amazing puzzle! Particularly enjoyed the multitude of different types of logic that had to/could be applied to solve it. Thanks!

on 25. July 2022, 14:06 by SirWoezel
Very tricky and at least as beautiful.

on 25. July 2022, 07:32 by Niverio
Very enjoyable and surprisingly smooth!

Last changed on 25. July 2022, 05:01

on 25. July 2022, 04:48 by RJBlarmo
Ruleset sounds pretty insane at first but the solve went quite smoothly for me. Lots of fun, thanks for setting!

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Wow, that was a fast solve. Thanks for solving and I'm glad you enjoyed it! It certainly was a very difficult set for me, I've come back to this idea on and off for close to a month now, and I'm very glad I was finally able to make it work in a smooth way.

Last changed on 25. July 2022, 05:01

on 25. July 2022, 03:39 by Vebby
Mind-boggling, a real test! Very satisfying to solve. Amazing feat to construct this, oh evil setter, though I fear you suffered the worst DOS out of this entire escapade.

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True, I definitely did DOS myself while setting this, haha

Difficulty:5
Rating:96 %
Solved:34 times
Observed:4 times
ID:000AKS

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Solution code:

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