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Japanese Crossroads: by Phistomefel: The Example Puzzle
🕑 Added 2024-07-08 12:00:09 +0000 UTCIt's just been brought to our attention that there is a new Phistomefel puzzle on Logic Masters. It's called Japanese Crossroads and apparently it's quite hard (!) Phistomefel himself recommends attempting an example he's constructed before trying the real thing. How hard can an example really be, we thought.... well, in this bonus video, Simon find out!!
Play the puzzle at the link below:
https://sudokupad.app/ibruw9r83g
Rules:
(NB The version of rule 7 below is CORRECT and worded slightly differently from that in the sudokupad link above so use this version when solving the puzzle).
1. Shade some of the cells and write a number from 1 to 6 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 6.
2. A loop runs through the shaded cells. Every shaded cell is part of the loop. The loop may not branch, but it may cross itself.
3. 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.
4. 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.
5. '??' represents some number which is greater than 9.
6. '*' represents any number of sets of consecutive unshaded cells with arbitrary sums including no unshaded cells at all.
7. If clues are given in a row or column, every consecutive set of unshaded cells is accounted for by Japanese Sum clues.
The full puzzle can be accessed at this link:
https://logic-masters.de/Raetselportal/Raetsel/zeigen.php?id=000IQB
Simon will try to find an enormous window of time to record an attempt at it soon!
Comments
Twizzy
Please please try it, it was really good!
Matteo Lanzarotta
Hi Simon, I'm on the edge of my seat for this solve! Maybe even a live stream 👀
Paolo De Leva
First, please find time to solve Phistomefel's outstanding and stratospherically innovative "Region Sum Clones," included in the 600k celebration pack.
Julia G
Update... I've solved it! Total time, ahem, 406 minutes (working on an off over several days, but I spent HOURS stuck at one point which actually wasn't hard in retrospect, I was just missing one thing repeatedly). I am normally slower than Simon, but still be super impressed if Simon videos it in under 2 hours (and I'll watch it, even having solved it, just a fab puzzle). I'm solver 101 - just outside the first hundred, but I'm just delighted. It was a fascinating puzzle at every stage of the solve. It's a particularly chewy puzzle as the combo of the loop (locally and globally) and the Japanese sums are not intuitive (to me at least). And they interplay the whole way. This is somewhat true in the example puzzle, but the big puzzle is.. big, so there's a lot more places to be looking for the next steps. Only technique hints I picked up were to use the roundabout on pen tool to mark squares with loop which could still be crossroads. Also used red crosses on edge of grid to mark which Japanese sum clues still have something to say, to help narrow focus.
Twizzy
The rules kinda need another addition from logic masters; a mention of the loop only moving orthogonally. I got stuck for a bit until I went to check the page.
Julia G
"Simon will try to find an enormous window of time to record an attempt at it soon!".. please please do so! I've been stuck at the same spot on the full puzzle for 3 days now. I just can't bear to close that tab! I'm sure I'm missing something simple.
