Khamodo Dragon (Japanese Sum Chaos Deconstruction)
(Published on 25. August 2025, 05:25 by MaizeGator)
This puzzle was set for round one of the Puzzle Agency Championship, which prompted contestants to use Knapp Daneben (off-by-one) clues.
- Chaos Deconstruction: Within the 12x12 grid, there are 9 regions, each consisting of 9 connected cells (not necessarily 3x3 boxes). Place all digits 1-9 into each region such that no digit repeats in a row, column, or region. Regions cannot touch orthogonally, but they may touch diagonally. Cells outside of regions remain empty.
- Japanese Sums (Knapp Daneban): Clues outside the grid give the sums of contiguous cells in regions for that row or column, delimited by empty cells. All clues are either one lesser or one greater than the true sum.
- Japanese Sum clues are given in the correct order, but the number of clues is also knapp daneban (off-by-one). That is, for each set of clues in a row or column, either one clue is omitted, or there is an extra (superfluous) clue given. (Clarifications: an extra clue may be inserted in any position in the string of clues, and the absence of clues in a row or column indicates "no information, not necessarily 0 or 1 groups).
Solution code: Column 12 (The last column), top-to-bottom, with “X” for empty cells
Comments
on 28. August 2025, 14:26 by MagnusJosefsson
Fantastic! Very fun combination, challenging but smooth and rewarding!
on 26. August 2025, 16:38 by MaizeGator
Clarified rules
on 25. August 2025, 18:49 by henrypijames
Wow, that's one of the most evil liar rules I've ever seen! 5½ difficulty - so one of those harder-than-5-out-of-5 puzzles. And I'm amazed how many solves it's got in a short time.
But it's unclear - even from the example - whether a missing clue can be inserted into any position, or only at either end. It should also be stated explicitly that empty clue means "no information", and not "zero plus/minus one section".
on 25. August 2025, 14:17 by Christounet
Great puzzle ! Loved the double KD ruleset. Thanks :)
on 25. August 2025, 13:53 by MaizeGator
Fixed prompt of solution code (thanks han233ing!)
on 25. August 2025, 12:44 by damasosos92
Wild, wild stuff.
on 25. August 2025, 12:38 by Agent
Great puzzle, a good mix of arithmetic and geometry, and many satisfying moments throughout!
on 25. August 2025, 11:27 by han233ing
Really cool puzzle! Whether it's locating regions or inferring outside clues, it all brings a sense of enjoyment.
(btw, the last column is c12.)
on 25. August 2025, 10:07 by Niverio
Really really difficult, but also pretty satisfying!
on 25. August 2025, 08:12 by Playmaker6174
Among all of the hybrid puzzles I've solved, I think this one easily has one of the maddest rulesets I can imagine, and the solve was as how I expected if not even madder xD
Nonetheless, what a rewarding and wonderful puzzle! Very interesting first half to work out, then there's one rather unexpected particular point in the middle and after that it still remained very consistent till the very end, but I'm happy to see that such mad ruleset can even work at all :)
on 25. August 2025, 05:31 by sfushidahardy
Really hard! Loved the wide variety of logic.
