Friendly X-Sums (Chaos Construction)
(Published on 16. July 2022, 23:11 by thoughtbyte)
Chaos construction: place one of each digit 1-9 in every row, column, and region, but the regions must be determined by the solver. That is, divide the grid into 9 orthogonally connected groups of 9 cells.
Friendly X-sums: if a cell contains its row or column number then it is friendly. Clues outside the grid represent any positive integers and they show the sum of the first X digits from that direction where X is the first digit and the Xth digit is the first friendly cell from that direction. All cells included in the sum are in the same region and the cell after the friendly cell is in a different region.
Cells separated by a grey square are in the same region. Cells containing a grey circle are odd.
F-Puzzles: https://f-puzzles.com/?id=2dmqtovd
CTC: https://tinyurl.com/friendlyxsumssudoku
Here is an example with some valid partial regions given the friendly X-sum clues:
Solution code: Row 4, row 6.
Comments
on 26. February 2024, 16:10 by Myxo
Amazing construction!
on 21. July 2022, 15:41 by MagnusJosefsson
Very nice challenging and cool puzzle!
on 19. July 2022, 18:53 by hepcecob
Oh boy was this clever. Enjoyed it very much, there were a couple of times I even went "no f***ing way" due to how the logic worked out, and very far into the puzzle as well.
on 19. July 2022, 14:42 by peacherwu2
Very beautiful puzzle and thank you!
on 18. July 2022, 19:49 by wenchang
Very nice and hard.
https://youtu.be/nA6IxGXRHCA
on 18. July 2022, 14:10 by thoughtbyte
Thank you for the kind comments @Kworb! Thank you @Jesper, your feedback is much appreciated as your puzzles have been an inspiration!
on 18. July 2022, 14:09 by thoughtbyte
Updated difficulty.
on 18. July 2022, 13:36 by Jesper
Very challenging, but ultimately rewarding, thanks!
on 18. July 2022, 08:18 by Kworb
Wow, very satisfying to finally figure it out. Incredible amount of logic for such a sparse grid. I had to work hard for every digit. Awesome puzzle, highly recommended.
on 17. July 2022, 22:30 by thoughtbyte
Thank you @marcmees, I'm glad you enjoyed it! And thanks also to @henrypijames for your testing, nice feedback, and letting me know I had an incorrect solution code!
on 17. July 2022, 17:56 by marcmees
Highly entertaining. thanks.
on 17. July 2022, 08:32 by thoughtbyte
fix solution code
