Double Counting
(Published on 17. December 2025, 20:46 by ralphwaldo1)
Composed for Scojo's prompt for extra regions.
The idea (and the diamonds) come from this problem from MathGuy_12
Normal Sudoku rules: Place a digit from 1-8 in each cell such that there are no repeats within any row, column or box.
Yin Yang: shade some cells so that all shaded cells are orthogonally connected, all unshaded cells are orthogonally connected, and every 2x2 contains at least one of each.
The value of a shaded cell is double that of its digit, and the value of an unshaded cell is its digit.
Diamonds and Circles: Values in ALL shapes count the number of cells seen orthogonally sharing the same shading as the cell (including the cell itself; the view interrupted by opposite shading).
Extra regions: digits in both Diamonds and Large Circles are set of 1-8. (Small circles may repeat).
Solution code: Unshaded cells in row 4 and row 5
Last changed on on 29. January 2026, 01:00
Solved by aqjhs, Scojo, Alce, Elker, Altynbek , jkuo7, monaters, karlmortenlunna, PuzzBmcg, WvdWest
Comments
on 29. January 2026, 01:00 by ralphwaldo1
rule clarification
Last changed on 23. January 2026, 14:31
on 29. December 2025, 02:12 by PuzzBmcg
Is something missing from the rules? What are the small circles for?
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bellal: Small circles also count shaded/unshaded, but aren't an extra set and may repeat
