Yin Yang +/-1
(Published on 7. August 2026, 01:54 by Jrosas)
Ordinary Sudoku rules. Place the digits 1 to 9 in every row, column and 3x3 bold outlined box.
Ordinary Yin Yang rule: the grid contains two (and only two) distinct regions. No 2x2 square of cells is entirely in either region, and each cell shares an edge with at least one other cell in its region.
+/-1 lines: Adjacent cells along each line share a yin Yang region and their digits differ by 1. ALL possible lines are given.
Circles: A digit in a circle indicates how many circles contain that digit AND a digit in a circle in a yin Yang region indicates how many cells containing that digit are in that yin Yang region. ALL possible circles are given.
LINK TO PUZZLE:
Solution code: Row 9
Comments
on 12. August 2026, 00:55 by Jrosas
I posted a harder puzzle using this same rule set called “Setting Things Straight.” Please check it out.
on 8. August 2026, 18:10 by Miatc
I kept waiting to have to use the negative constraint on the circles, but didn't end up having to. Lovely puzzle nonetheless
[reply: It is interesting that people find different logical paths. I use the circles and their negative constraint very early in the solve. I would like to set a puzzle with these rules that needs that negative constraint at the very end for the last deduction. I’m glad you enjoyed this one, though.]
on 7. August 2026, 16:30 by Jrosas
Clarified “region”
on 7. August 2026, 16:07 by Franjo
Thank you very much for creating and sharing this lovely and approachable YY-hybrid. Near the end I found a deadly pattern - of course it didn’t exist if you carefully read the rules …
on 7. August 2026, 15:10 by Plok
I read this rule 20 times. I assumed a 3x3 region. But you call the YY areas also regions. Suggestion to change the rule into:
+/-1 lines: Adjacent cells along each line share a Yin/Yang region and their digits differ by 1. ALL possible lines are given.
Similar for the next rule:
Circles: A digit in a circle indicates how many circles contain that digit AND a digit in a circle in a certain Yin/Yang region indicates how many cells containing that digit are in that samen region. ALL possible circles are given.
Great puzzle!!
[reply: thank you for the comment clarifying that “region” means “box” to some people. I will change the rule here on LM and later I will change it on Sudokupad.]
on 7. August 2026, 12:47 by anothermember
I don't understand how "ALL possible circles are given" is meant to be interpreted, but I started solving and retroactively interpreted it as "same digits within the same region are consistently circled/un-circled" and that lead to the solution. Don't know if I skipped a logical step there or not.
[reply: I have thought about this comment for some time and I cannot think of a second way to interpret the circle rule paragraph. I set several different yin Yang puzzles with the line rule and without the circle rule. I could not find a way to solve them, so I added the circle rule and it solved this puzzle. I might try to set another puzzle with the identical rules and a lot more circles.]
on 7. August 2026, 10:43 by Jrosas
Fixed picture
on 7. August 2026, 10:11 by mihel111
What a lovely YY puzzle. Very approachable. I gave it 2* for difficulty. The use of negative constraints for the late disambiguation is quite cool.
Very well done.
on 7. August 2026, 08:56 by unlogical
Very nice puzzle, thanks!
Note: The puzzle screenshot above is horizontally flipped compared to the one in the link ;)
[reply: that’s interesting. I do not know how that happened. Thank you for commenting.]
[reply: I figured it out. Thanks again.]
