The Odd Couple (Dutch Flats/Parity)
(Published on 26. May 2025, 01:59 by damo_89)
Messing around with parity in conjunction with the Dutch flatmate constraint I came across some interesting interactions. Sadly, parity lines don't disambiguate the digits 234678 so I had to pair this with something and chose Numbered Rooms. As this uses a combination of constraints this is ineligible to be released as an official part of the Dutch Flat Mates series by Flinty, so is being released as a bootleg. Good luck!
- Normal sudoku rules apply: Place the digits 1 to 9 once each in every row, column, and 3x3 box
- Dutch Flat Mates: Every 5 in the grid must have a 1 directly above it or a 9 directly below it. It may have both, but it doesn't need both
- Parity Line: Two adjacent cells along a red parity line must contain one odd and one even digit
- Numbered Rooms: Clues outside the grid give the digit to be placed in the Nth position in that row or column, where N is the digit in the first position
Solution code: Row 5
Comments
on 3. June 2025, 08:39 by kirstytortoise
Thanks for the puzzle - I enjoyed it! The Dutch Flatmates series had some puzzles with multiple constraints early on, presumably for similar reasons. Dutch Flatmates is a good rule for breaking high-low symmetry, but it can't help with 234678.
on 27. May 2025, 09:06 by ThisIsHardcore
god, this was hard but very fun :) thank you guys so much for the explanation, i really appreciate it! i'm very new to logic masters and complex puzzles in general, and i'm very thankful for all the peeps out there who take the time out to explain the basics to noobs like me. :)
on 26. May 2025, 13:13 by da-hans
Nice puzzle
on 26. May 2025, 12:16 by da-hans
@ThisIsHardcore
Example: R3C1 gives the position of the 5 in that row. Index starts from the clue. So if it is a 3, 5 has to be in R3C3, if it is a 6, 5 has to be in R3C6
on 26. May 2025, 10:46 by ThisIsHardcore
hey damo_89, this seems like a really cool puzzle; however, i've been re-reading the "numbered rooms" rule for the past 10 min and can't wrap my head around it. i checked the solution guide and i still don't understand the relation between the numbers outside the grid and the inside of the grid. could you explain this to me? thank u :)
Damo: thanks for giving this a try. da-hans has given a good explanation above and I will probably just repeat the same, but numbered rooms work a bit like indexing. Take the 5 clue in row 3. If the first digit in row 3 is a 4, then 5 is placed in the 4th position in the row, I.e. 5 is in r3c4.
The 3 clue under c7. If the first digit, r9c7, were a 9, then the digit 3 should be placed in the 9th position, I.e. 3 is in r1c7.
I hope this clarifies things and good luck.
