Full Folding Frenzy
(Published on 22. December 2024, 00:40 by ThePedallingPianist)
Mad Fold-In is a new puzzle genre introduced by Gnubeutel and beautifully animated by OlliWright. Nebuzaradan and The Book Wyrm gave me helpful feedback regarding my wording of the rules, and I ended up borrowing heavily from the way gdc presents them. Special thanks to my dad for once again being my sounding board while I tried to justify some of the crazier logic to myself, and to Sotehr for fully testing an earlier version of this and (just about!) convincing me to add a couple of clues to smooth out the solve path a little!
Normal sudoku rules apply within the central 9x9 grid.
Mad Fold-In: The dashed red lines can be folded onto each other so that columns 1, 2, 8 and 9 form a 4x9 grid (i.e. columns 3-7 disappear).
Full Rank: In a 9x9 grid, a total of 36 nine-digit numbers can be read in the rows and columns, each viewed from both directions. If these are listed in ascending order, a "full rank clue" indicates the position in this list of the nine-digit number seen from the clue, where a "1" clue would indicated the lowest nine-digit number and a "36" clue would indicate the highest. In a 4x9 grid, a similar list can be made with 26 entries, 18 of which have four digits.
Full Rank Differences: A clue outside the grid in this puzzle shows the DIFFERENCE between the value of the full rank clue in that location as it would appear in the 9x9 grid and the value of the full rank clue in that location as it would appear in the folded 4x9 grid.
(Clarifications: There are no tied ranks, i.e. identical rows/columns, even in the 4x9 grid. Differences are absolute, i.e. if the value of a full rank clue for the 9x9 minus the value for the 4x9 grid is negative, the clue displayed will still be positive. The outer cells have been provided for note-taking purposes only.)
Solution code: The 4 digits of the row ranked 7 in the 4x9 grid
Comments
on 25. January 2025, 15:11 by rich_27
God this one almost broke me. I spent so long before even getting to what felt like breaking in! Probably somewhere around 15 hours to solve this one for me!
on 19. January 2025, 06:26 by Silverstep
Brutal. Certified Filuta-grade. Chocked-full of beautiful theorems and surprising results. Hats off to those who solved this one online I have no idea how you did it
on 9. January 2025, 02:53 by The Book Wyrm
I don't think it had to be done, actually, but I'm glad that you did. This puzzle is mad. So much crazy and intricate logic, very a very interesting variation on full rank that leads to some cool deductions.
Really enjoyed figuring out all the tricks in this one, thanks for the puzzle.
on 2. January 2025, 21:57 by Flinty
Easy dubz... Solid 2/5 difficulty. My strategy, watch Scojo stream it, occassionally offer terrible logic, claim the solve. Incredible stuff.
on 28. December 2024, 07:38 by mnasti2
Neat idea and very nice execution!
on 23. December 2024, 01:16 by ralphwaldo1
That was a breeze, for people used to standing behind jet engines
on 22. December 2024, 08:07 by Sotehr
Insanity! I am loving the updated version, though.
