Second Rodeo (collab. with Tallcat)
(Published on 17. October 2024, 23:06 by jwsinclair)
Second Rodeo, by James Sinclair and Tallcat
Divide the grid into nine orthogonally connected nine-cell regions, and place the digits 1-9 once in each row, column, and region.
A digit inside a circle indicates the sum of all digits in the same region that see that cell by knight's move.
A digit inside a square indicates the total number of cells in the same region that see that cell by knight's move.
A digit inside a diamond indicates the total number of *other* regions with at least one cell seen by knight's move from that cell.
SudokuPad
Some backstory:
A few weeks ago I published my first-ever chaos construction, First Rodeo. Tallcat reached out to say some nice things about it, and, like a maniac, I was like "I'm working on an even better follow-up but can't get past the break-in, want to help?!?" Inexplicably, he did want to help, and continued helping even after he found the fundamental flaw in my break-in.
Some very interesting ideas emerged from that initial exchange, and we made some slight changes and kept working. Eventually we scrapped my original break-in altogether (this was my suggestion, and I'd argue my single most important contribution to the project), allowing us to more freely use all the bits of logic we'd found that refused to play nicely in the earlier drafts.
I won't say much more about the resulting puzzle, but it's very difficult, and we're both very proud of it. Hope you enjoy :)
Solution code: row six, with a dash ("-") to indicate each region border
Comments
on 16. January 2025, 21:43 by cirne
I appear to have done something extremely strange! I've solved the puzzle according to both Sudokupad and lmde, but I must have done something wrong with the chaos construction because the bottom-right diamond has the wrong digit! I'm absolutely flummoxed; I can't even tell how I'd adjust my region boundaries to fix this while still maintaining all the rules.
That said: thank you for a delightful puzzle, even if I apparently solved it improperly! I especially enjoyed the reveal of r5c5's importance
on 1. January 2025, 21:04 by askaksaksask
I was reading an old entry in your newsletter and I realized I forgot to come back to the second rodeo! This was a wonderful extension of the first rodeo, I greatly enjoyed it. Some tough deductions, but a beautiful chaos entry nonetheless. Thank you!
on 4. December 2024, 02:02 by ViKingPrime
Beautiful Chaos Construction.
on 25. October 2024, 23:28 by Fool on Hill
Brilliantly constructed: I enjoyed the solve a lot - a really finely tuned challenge at the hard end of puzzles I have solved.
on 25. October 2024, 06:18 by Norkas
That was ahard puzzle. And also really fun. Thank you two for setting
on 22. October 2024, 17:43 by henrypijames
Quite brilliant but really hard, astonished it's got so many solves.
on 18. October 2024, 21:56 by marcmees
great CC. thanks
on 18. October 2024, 10:50 by Snookerfan
Great puzzle! Loved every minute of the solve. Thank you
on 18. October 2024, 04:59 by bansalsaab
3 hrs of pure fun. Amazing construction.
on 18. October 2024, 03:45 by MSDOS
Took a couple of days on and off to work through this one, but thouroughly enjoyed the solve! Definitely some pretty tricky spots, but I did really like the logic that the extra clue type (diamonds) brings, especially for the break in! Great construction from the both of you!
on 18. October 2024, 03:25 by MaizeGator
I love James's self-deprecation; it's highly amusing coming from such an accomplished setter.
Anyway, this puzzle is a ton of fun, featuring sublime region-building and tricky-to-spot yet satisfying sudoku deductions.
on 17. October 2024, 23:48 by tallcat
@bansalsaab. The diamond only counts other regions that it sees. For example, if it sees three cells and one of the cells is in the same region as the diamond but the other two are in a different region (but the same one), the count would be 1. Hope this helps. In your example, the count would also be 1 (as it sees 1 other region)
on 17. October 2024, 23:42 by bansalsaab
Hello, For the diamond clue, if there are 2 other cells but they belong to same other region, will that be counted as 1 or 2?
--
Yes, what Tallcat said. If the diamond cell sees two (or more) cells from the same region,* it only counts as one.
*Assuming those cells are in a different region from the diamond cell; if they're in the same region, they aren't counted at all.
