Japanese Crossroads
(Published on 30. June 2024, 19:49 by Phistomefel)
If you are not yet familar with loop puzzles which allow crossings, it is probably very easy to make errors in this puzzle. My recommendation is therefore to get acquainted with it by first solving the given example.
Here are the rules:
- Shade some of the cells and write a number from 1 to 9 in every unshaded cell such that no digit repeats within a row or column. Shaded cells cannot contain numbers. A row or column does not necessarily contain every digit from 1 to 9.
- A loop runs through orthogonally the shaded cells. Every shaded cell is part of the loop. The loop may not branch, but it may cross itself, with the two loop sections going straight.
- The clues outside of the grid are Japanese Sum clues. A number indicates the sum of the digits in a consecutive set of unshaded cells. The clues are given in the right order.
- A single '?' represents a single digit from 1 to 9. Combined with another digit, '?' can also be 0, as long as it is not the leading digit. E.g. '1?' could be any number from 10 to 19 and '?4' can be 14, 24, 34 or 44.
- '??' represents some number which is greater than 9.
- '*' represents any number of sets of consecutive unshaded cells with arbitrary sums including no unshaded cells at all.
- If clues are given in a row or column, every consecutive set of unshaded cell is accounted for by Japanese Sum clues.
If you want to try the example you can solve it online via Penpa Plus (with solution check) or SudokuPad (without solution check).
The actual puzzle is also available online via Penpa Plus (with solution check) and SudokuPad (without solution check). Have fun solving!
Solution code: Penultimate row and third column
For an unshaded cell write the number in it into the solution code. For a shaded cell, write I for a straight piece, L for a bend and X for a crossing.
In the example, the solution code would be:
5LIL1LXL LL13I5I4
Comments
on 17. August 2024, 07:29 by Phistomefel
Updated rules in puzzle links.
on 17. August 2024, 01:48 by wazdra
Would it be possible to edit rule 7 also in the CTC-App ? I had misunderstood too ^^
on 9. August 2024, 23:15 by Guaste
Incredible puzzle
on 2. August 2024, 21:57 by Myxo
Amazing!! So many intricate cool steps.
on 15. July 2024, 15:46 by madhupt
This was so difficult but I’m glad I was able to solve it finally. Nice to find that I had also reached the exact same position as given by Phistomefel in his explanatory post. The way forward from here was also more or less the same! Yay!
on 12. July 2024, 15:37 by tonald
Wow. The crossings make things fun.
on 11. July 2024, 16:47 by ErnoWindt
Thank you. I feel smarter every time I solve one of your puzzles, no matter how long it takes me. :)
on 9. July 2024, 06:14 by Phistomefel
Added a detail to rule 2. Thanks to Uskok!
on 9. July 2024, 01:58 by Uskok
Maybe the rules should specify that the loop runs orthogonally.
on 3. July 2024, 02:52 by kamkam
It took me 3 hours to finish this sudoku and I honestly thought I broke it many times, not considering the fact that the loop could cross. This is a true masterpiece by the way.
on 2. July 2024, 13:43 by Christounet
Awesome puzzle ! There are indeed so few clues to work with in the midsolve that one has really pause and think to go further. Thanks :)
on 2. July 2024, 04:44 by Agent
Excellent puzzle, I learned a lot!
on 1. July 2024, 11:28 by Piatato
Awesome puzzle, thanks!
on 1. July 2024, 06:45 by Phistomefel
Error in rule 7 corrected. Thanks to Piatato for pointing it out!
on 1. July 2024, 00:44 by Jesper
Great puzzle, enjoyed it a lot, thanks!
on 30. June 2024, 22:00 by ONeill
Very cool and very tricky indeed! thanks :)
on 30. June 2024, 21:12 by KNT
Wow - the midsolve of this one is an absolute gauntlet. Really tricky.
Possibly one of your less-telegraphed puzzles, but in a good way; the solver really needs to understand what is going on to be able to ask the right questions.
Thanks for this puzzle!
