kNights, uNite!
(Published on 17. July 2020, 02:33 by Alphish)
Not anymore!
The knights rose up against monarchy and founded a new order.
With that, no one was left without a comrade and there was much rejoicing (among knights, that is; kings may beg to differ).
RULES:
Each row, column and 9-cell region must contain all digits from 1 to 9.
Additionally, each value must see one or more identical values by a chess knight's move (2 cells forward, 1 cell to the side).
For example, if cell R1C2 has value of 7, then at least one of cells (potentially many) R3C1, R3C3 or R2C4 must also contain a 7.
Special thanks to Yosh for giving some inspiration/ideas (in particular the N-shaped arrangement of given digits).
Solution code: Row 1 (left to right), column 8 (top to bottom)
Comments
on 27. September 2024, 14:02 by Jrosas
Fun
on 24. September 2024, 17:35 by Jrosas
Sudoku pad without solution: https://sudokupad.app/0fsdlazhoi
on 23. July 2020, 17:26 by Nylimb
For what it's worth, it is possible to create a grid like this using 9 connected regions. View this in a fixed-width font:
+-------+-----------+-------+-------+
|.7...6.|.5...9...4.|.3...1.|.2...8.|
|.......+---+.......|.......+---+...|
|.5...9...4.|.6...3.|.2...8...7.|.1.|
|...+-------+...+---+...+-------+...|
|.8.|.7...2...1.|.9...6.|.3...5...4.|
|...+-------+...+---+...+---+.......|
|.2...1...3.|.8.|.6.|.5...4.|.9...7.|
+-----------+---+...+---+---+...+---+
|.4...8...7.|.3...1...9.|.2.|.6.|.5.|
|...+-------+.......+---+...+---+...|
|.9.|.3...1.|.4...5.|.7...6.|.8...2.|
|...|.......|.......|.......+---+...|
|.1.|.4...9.|.2...7.|.8...5...3.|.6.|
|...+---+...+---+...|...+-------+...|
|.3...2.|.6...5.|.8.|.1.|.7...4...9.|
|.......|.......+---+...+---+.......|
|.6...5.|.8...7...2.|.4...9.|.1...3.|
+-------+-----------+-------+-------+
I did some programming to generate random knights-united grids (without regions) and give a numerical measure of the clustering that Realshaggy mentioned. I chose the one with the least clustering, and then worked by hand to construct the regions.
There are probably many others, but I don't have an efficient way to generate them.
I don't know if this can be turned into a good puzzle.
on 17. July 2020, 22:11 by aneoid
Thank you, Alphish. Thank you very much.
on 17. July 2020, 18:41 by marcmees
wow ... impressive puzzle. satisfying solve. thanks
on 17. July 2020, 17:04 by Alphish
Added the printable version link.
on 17. July 2020, 14:44 by SudokuExplorer
This is a very neat concept. I haven't solved this yet, but the start of this puzzle is very nice. I'm thinking of introducing a pro-queen constraint just for the queens in a hopefully future queendom sudoku (with conflict). I wonder if a sudoku with every digit having a pro-queen constraint is possible, like this pro-knight sudoku?
on 17. July 2020, 10:15 by stefliew
That was absolutely stunning! One of the most phenomenal placement-based puzzles I've had the pleasure of solving. Thank you for that beautiful puzzle!
on 17. July 2020, 10:00 by Realshaggy
Interesting. A while ago, I tried to do an "Anti-Anti-Knight" puzzle, where like in this puzzle, each cell contradicts the Antiknight constraint. Obviously, a standard grid is not possible, because of the corners. I was not successful, but I only tried some symmetric grid layouts.
I also looked at a few "solutions" I found with computer help, that you get, if you ignore regions completely. It seemed hard to draw nine connected regions in such a grid, because typically, same digits appeared in clusters close to each other. So in a typical solution you had a lot of 1s in the upper right and a lot of 9s in the lower left, and it was hard to draw enough regions to connect all of those digits. I missed the idea of introducing an extra region though.
Nice to see that idea put into a puzzle.
One small remark: Despite the rise of Penpa and F-puzzles, a lot of people like me still print the puzzles and prefer solving on paper. So it would be nice to avoid colors if it's not necessary for the puzzle. (Especially dark ones like the blue you use.)
on 17. July 2020, 03:45 by glum_hippo
The yellow squares are an 'extra region' that contains 9 cells with 9 unique digits
on 17. July 2020, 03:26 by RockyRoer
What’s with the yellow squares?
on 17. July 2020, 02:53 by Circleconstant314
I tested this puzzle and I gotta say, I can't recommend it highly enough. Do give it a go!
