Snakes Sandwiches & Chaos
(Published on 8. August 2020, 04:39 by emmettcito)
I was almost finished with my puzzle when I noticed I accidentally erased most of the borders between the regions. If only there was a way to put it back together...
Rules: Fill each row, column and region with the numbers 1 to 9. These regions are to be determined, and given regional borders in the grid must be respected. No cell can be orthogonality adjacent to more than 2 cells within the same region, which implies that all regions are snake shaped. Small numbers in the upper left corners of cells denote the sum of the numbers between the 1 and the 9 in the region that the number is in.
Solution code: Row 2 followed by column 8
Comments
on 25. October 2023, 02:11 by DiMono
I put this into penpa for anyone else who wants to solve it, with answer check. https://tinyurl.com/yvz83fqs
on 22. April 2022, 22:05 by marcmees
nice. thanks.
on 11. August 2020, 22:23 by emmettcito
@henrypijames It probably happens just as often when you overlook a false path as a true path, but you don’t notice most of the times you overlook a false path so it seems like you overlook true paths more when that is in fact not the case.
on 11. August 2020, 08:17 by henrypijames
You guys are right of course. This wasn't the first time - nor would it have been the last - that I overlooked a possibility that luckily turned out to be false. Of course, what happens much more often is the opposite: me missing a possibility that would turn out to be part of the solution.
on 10. August 2020, 20:35 by emmettcito
@henrypijames A puzzle that uses region determination and digit placement intertwined in the solution path is definitely the most enjoyable type but it is extremely hard to configure a puzzle like that. When I constructed this I started with an already planned region layout and played with the sandwich clues, and once I had working sandwich clues I started removing region borders. Unfortunately the way I had it configured didn't allow me to create that type of puzzle. But I am definitely going to try to make puzzles more like that in the future if I can. Phistomefel's Araf Killer Sudoku and hamslice's Shattered Palindrome - Equal Sums are both amazing examples of how this can be pulled off.
on 10. August 2020, 20:23 by emmettcito
Changed difficulty to 4 stars
on 10. August 2020, 20:16 by emmettcito
Added one region border in the top left to make the solution path more logical.
on 10. August 2020, 17:41 by henrypijames
Both the snakes and the remaining sudoku were quite hard (though not 5-star hard, I reckon) - hard to believed they were solvable based on so little information.
But this puzzle would be even more interesting (and probably also harder) if instead of solving the regions first and the sudoku afterwards, you have to switch between the two - drawing some snakes, filling some digits, which helps you draw more snakes, which in turn helps with the digits, and so on.
The Snake Sum series by Quarterthru (or at least some puzzles in that series) has required this kind of intricate solving process. I don't know if it's possible here, but you'd definitely need to provide more digits and less borders.
on 8. August 2020, 16:23 by MartinR
Quite tricky, although it helped that I've also set an irregular sandwich recently (non-chaos though) so had gone through the "how do I make every region one cell wide" many times in testing :)
