Day 22: Yin-Yan
(Published on 22. December 2025, 06:00 by SharpFox)
Rules:
- Normal 4×4 Sudoku rules.
- Yin-Yan: Shade some cells such that both the shaded and the unshaded cells are orthogonally connected and no 2×2 square is either fully shaded or entirely unshaded.
- Red lines mark borders of differently shaded cells. Red crosses give the number of cells with the same shading among the (up to) 8 surrounding cells including itself.
- Orthogonally adjacent cells of the same shading have different parity i.e. one digit is odd and one even.
- Tiny tip: In this puzzle yin and yan are symmetrical i.e. it doesn't change anything if you change the shaded and unshaded cells.
Solution code: Row 1 (4 digits):
Last changed on -
Solved by maniacaljackal, EFlatMinor, Lissa41585, Donatello_86 , Dee_Code, tiuhto, Dermerlin, superkinkel, xrrx, pepe74287, rcg, 3ColorTheorem, kehan628, Fizz, marcmees, walid_tun, patolucatis, Gizmo, ... scushuaishuai, Uhu, ManuH, ffricke, pjot, Kleiner_Lateiner, Senjo, andrew_doe, hampterss, Morisenseiisgod, ethteck, stafen, geronimo92, Raistlen, pzwack, BlackApolloX, mmmead, Saltman, Saskia11
Comments
Last changed on 25. December 2025, 04:52
on 25. December 2025, 04:52 by FireTruckFuel
This puzzle seemed somewhat daunting given the rules so I read them through twice. Finished in only 1:13. I think my trepidation says more about my familiarity with Yin-Yan than it does about the puzzle itself. My favorite 4x4 of the series!
on 24. December 2025, 18:01 by tstaffor
The parity rule is very interesting for a shading puzzle.
on 22. December 2025, 19:19 by Fisherman
Happy holidays to all.
