Sandwich Sudoku
(Published on 15. July 2021, 18:33 by kolot)
I decided to post my sudoku puzzles into LMD. I am planning to post one puzzle a week and I wanted to start with one of my best puzzles.
This puzzle is a regular sandwich sudoku with no extra rules, only one given digit (which has to be given since otherwise 1s and 9s can be switched), and only 10 of the 18 sandwich clues given. If anyone has seen a sandwich sudoku with less given clues, please let me know.
This puzzle might be very difficult but it requires no bifurcation at all. To be able to solve this puzzle, you have to discover a fact that holds for any sandwich sudoku.
RULES: Normal sudoku rules apply. Clues outside the grid give the sum of the digits sandwiched between the 1 and the 9 in that row/column.
Any feedback is highly appreciated!
Solution code: Row 8 followed by column 8.
Comments
on 17. November 2023, 20:08 by KurtSchneider
I don't think I've seen a puzzle with this break-in before, it's very nice! really enjoyed solving this :)
on 17. December 2022, 01:10 by DiMono
It is absurd that this puzzle resolves as nicely as it does. It took me a while to get to it, but I have thoroughly enjoyed my time with this puzzle.
on 29. May 2022, 01:53 by Piatato
Very nice puzzle, although I feel a bit cheated, because I never discovered any general fact, I just used regular sandwich sudoku. :P To be fair, I got stuck at one point, and thought that I had finally come to the moment when my lack of understanding would be my downfall, but when I finally came back to the puzzle, I found the next deduction within five minutes, and the rest of the puzzle unfolded very smoothly from there. I’m wondering what weird fact I might still be ignorant about now …
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Thank you for solving the puzzle and for your very nice feedback. I am surprised that this puzzle can be solved by just using standard sandwich sudoku techniques. I have written the intended solution path in a hidden comment. You may see the fact that needs to be discovered in that comment.
on 28. April 2022, 16:43 by Playmaker6174
That was quite a mouthful of logics in this puzzle, looks totally baffled at first but once I started wrapping my head around the "supposed" general idea, things also started to unfold one by one slowly but not immediately. Very cool and miraculous puzzle :)
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Thank you so much for solving the puzzle and for your very kind and very valuable comments! I appreciate it.
on 28. April 2022, 14:05 by kolot
Minor change in the text.
on 28. April 2022, 14:04 by kolot
Link corrected.
on 28. April 2022, 14:02 by kolot
CTC app link is added.
on 13. April 2022, 23:20 by Qodec
I found this much more approachable than QaM. The way this puzzle suddenly clicks together is magic, loved it!
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Thank you so much for solving the puzzle. Right, once you get the main ideas there should be nothing very complicated. It is very good to see that you liked it.
on 11. August 2021, 08:21 by kolot
Tags changed
on 10. August 2021, 19:31 by kolot
Labels changed.
on 19. July 2021, 13:13 by zhergan
Amazing construction!! Thanks:)
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Thank you for solving it.
on 16. July 2021, 13:33 by cdwg2000
@kolot
Thank you for your detailed logic process, I learned a lot from it.
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You are welcome. I am happy to see that it was heplful.
on 16. July 2021, 08:24 by cdwg2000
This is the least sandwich clue I have seen so far. I didn't find any elegant logic, and it was difficult to get the answer after a few T&Es.
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I am happy to see that you solved it. Thanks! It does actually have an elegant solution. No bifurcation is necessary.
on 16. July 2021, 02:05 by cdwg2000
If no additional rules other than the sandwich Sudoku rules are given, there is no sandwich Sudoku without clues.
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Yes, but have you ever seen a sandwich sudoku with no extra rules, one given digit, and 10 or fewer given sandwich clues?
