Three Hole Punch Sudoku
(Published on 18. June 2020, 19:06 by RockyRoer)
The 'holes' inside certain letters and numbers are called "Counters". The numbers 4, 6, 9, 0 each have 1 counter, and 8 has 2 counters.
This sudoku is all about counters. Normal killer sudoku rules apply, with a few important additional rules:
- Every cage contains exactly three counters within both its cells, and the numbers in the sum itself. For example:
- A cage could contain the numbers 3469 which add up to 22, and there are three counters (the 4, 6, and 9)
- A cage could contain the numbers 4 and 6 which adds up to 10, and there are three counters (the 4, 6, and 0 in 10)
- A cage could contain the numbers 4 and 8 which adds up to 12, and there are three counters (the 4, and two from 8)
- The three counter symbol that shows in each cage is always in the largest cell in that cage.
- In purple around the outside of rows and columns, every row or column where the digits and sum of a sandwich (between 1 and 9) contains 3 counters the symbol is shown. (The counter in the 9 would not be counted, of course.)
- In green around the outside are little killer clues along every diagonal that contains three counters in both the sum and cells. Note, digits can repeat along little killer diagonals, so a diagonal of 4, 5, 3, 4 = 16 would be marked.
Oh, and one more thing, you'll need to figure out where all the cage sums belong. At least you know what they are. You can try the puzzle on Sven's Sudokupad
Solution code: Type in row 5 from left to right.
Comments
on 31. December 2025, 15:19 by RockyRoer
Added link and shorted solution code.
on 31. December 2025, 01:05 by ThePedallingPianist
Link with solution check:
https://sudokupad.app/xxg366ydb0
Also, we found that the negative constraint did NOT apply on diagonals.
Otherwise, really cool innovative ideas for a 2020 puzzle that have helped to shape the sudoku genre of the future! Thank you for setting :)
on 24. October 2025, 02:04 by Nell Gwyn
Why am I reminded of the first question of The Impossible Quiz...
on 24. October 2025, 00:15 by aqjhs
really nice!
i transcribed it to sudokupad
https://sudokupad.app/k6amy6uw3g
on 20. October 2025, 07:57 by isajo4002
Amazing puzzle although I don't think I used the sandwiches at all I kinda forgot that the little killer and sandwich clues even existed but amazing puzzle and I'm surprised that you can solve all but 4 cells with just using the killer and the maximum cells. Had a blast
on 25. March 2023, 16:05 by Vebby
Penpa+ link with answer check:
https://tinyurl.com/2rxwljxv
on 19. June 2020, 17:35 by Krokant
Funny and enjoyable variant.
What I learned while doing this: Counting counters is harder than it should be. ;-)
on 19. June 2020, 17:23 by RockyRoer
Nutz... had the wrong column in the solution code. I'm SO sorry if you tried this and found it wrong! Should be fixed now!
on 18. June 2020, 21:02 by RockyRoer
What I learned most about myself doing this: I don't actually draw my 4's with counters :-)
