Sum Line Sudoku #2
(Published on 8. October 2022, 12:57 by Phistomefel)
- Fill the grid with the numbers from 1 to 9 so that in each row, column, and 3x3 block, each digit occurs exactly once.
- For every triple of adjacent digits on a line, one of the digits has to be the sum of the other two, e.g. 2-5-7, 6-9-3, and 8-4-4 are valid adjacent digits along a line. Digits may repeat on a line if allowed by the other rules.
Here you can find a link to solve the example online.
The puzzle is also available online via F-Puzzles and CTC-App. Have fun solving!
Solution code: The last two columns
Comments
on 26. July 2025, 21:49 by StephenR
When I originally did this I needed a nudge from Simon at the start, but then managed on my own so pretty pleased with that. Some excellent logic packed in here as we have come to expect from the maestro.
on 31. May 2023, 16:49 by OldCaptainWZJ
Even with the logic I established in the previous puzzle, and even after seeing what this puzzle is about, it still has a lot of fresh logic to offer. Doing the previous puzzle did help with grasping this kind of restriction, so the difficulty isn't overwhelming for me.
on 8. February 2023, 23:24 by SudokuExplorer
Intriguing constraint! Both puzzles had a plethora of different ideas, which were a pleasure to uncover. Thanks! :-)
on 8. December 2022, 21:37 by Deathranger999
I don't normally try Phistomefel puzzles, or generally CTC video puzzles that are longer than an hour, but I decided to give this one a shot. To my surprise I actually found the break-in in not too long. After that the logic flowed really really nicely. Awesome puzzle, super happy to have solved it!
on 23. November 2022, 08:36 by PotatoHead21
Wow. This puzzle was super hard, Required lots of scanning and numerical analysis. I'm glad I was able to solve it.
on 5. November 2022, 16:18 by meixia
Even better than the first one. A lot more challenging too, but I don't mind a good challenge from time to time. Thank you for the puzzles!
on 30. October 2022, 10:40 by gurgilewis
Beautiful and so fun to solve. Such a clever idea and executed so well. The variety and synergy of the lines is incredible. Difficult, but once you figure out a strategy it's challenging but manageable.
on 11. October 2022, 18:02 by DiMono
Well that is certainly not what I expected the break-in to be! :D A more than worthy sequel to the first.
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Thanks a lot, DiMono! I am honored. Unfortunately, I had (and still have) no idea how to telegraph the break-in properly.
on 11. October 2022, 13:17 by Fool on Hill
Truly great puzzle - I was solving while distracted and it took me a while to work through the logic. Once I saw what was going it was a pretty tough puzzle, but solved really nicely with fresh things to think about at each stage,.
on 11. October 2022, 08:15 by cmb
Incredibly good but just as hard.
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Thank you so much, cmb!
on 11. October 2022, 01:11 by antiknight
That was a brutal and crazy break-in and it didn't stop after that. I did so many gorgeous deductions to solve the puzzle! I loved the logic around the lines in boxes 4 and 7 a lot! Thanks for sharing this amazing puzzle Phistomefel !
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Reading this, I am very glad that I redesigned the break-in to make it more accessible. And it's great to hear that the puzzle was to your liking. Thanks! :)
on 10. October 2022, 17:19 by drbs
The break-in was too difficult, but then the loop made me insane. Very nice!
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Glad you enjoyed the puzzle anyway. ^^;
on 10. October 2022, 17:03 by DVFrank
Ein wirklich großartiges Rätsel! :^)
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Vielen Dank, DVFrank! :^)
on 10. October 2022, 15:04 by GrizzledStoat
What a lovely lovely puzzle.
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Thank you so much! :)
on 10. October 2022, 13:46 by peacherwu2
Has to be this hard???
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No, it didn't have to be this hard. I just had a few pieces of logic I wanted to incorporate into the puzzle and it turned out this way.
on 10. October 2022, 12:47 by Fool on Hill
Brilliant, but very hard. The logic around the 3-cell lines in row 6 and column 4 was challenging and beautiful when I got to it. Somehow I made it through - very glad I put in the effort.
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Thank you, Fool on the Hill (by the way a very lovely book). The step you described came very naturally to life and I was glad with how it turned out.
on 9. October 2022, 20:08 by Playmaker6174
Stunning, intricate, challenging and engaging till the very end! The logic involved around box 1 and 2 was magical to witness, but the puzzle didn't really let it loose till the very end of the solve. Plenty of fresh and wonderful deductions throughout! ;)
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Thank you, Playmaker! I was quite astounded for the logic these lines allow for and I am glad you enjoyed it.
on 9. October 2022, 13:22 by Phistomefel
Thank you so much for wonderful feedback, everyone!
@TotallyNormalCat: I'm glad you liked this piece of logic, since I was particularly happy when I found it and got it working. :)
on 9. October 2022, 12:46 by Snookerfan
Great puzzle, very interesting all the way through! Thank you so much.
on 9. October 2022, 00:43 by Qodec
Fully delivering on the promise of the first puzzle. Beautiful fresh deductions in here!
on 8. October 2022, 21:36 by TotallyNormalCat
Amazing puzzle, I especially liked the logic around boxes 1,2 + the loop clue :)
on 8. October 2022, 21:09 by Phistomefel
Thank you so much for the kind words, Jesper and Piatato! I am glad you enjoyed the logical variety of the puzzle.
on 8. October 2022, 15:56 by Piatato
This constraint keeps fascinating me a lot! Thanks for the tough, but very interesting and nice puzzle :-)
on 8. October 2022, 14:52 by Jesper
Very nice! A lot of cool deductions, quite varied logic. Much more challenging than the first puzzle, in my view.
