Variant of sudoku I liked a lot, seen on this site, by Richard I think?
Every region contains eight different digits. One cell isn't part of any region.
Every row, every column must instead contain different digits 1 to 9.
Solution code: Row 3 and row 7
on 10. July 2018, 14:54 by Realshaggy
Just a small hint: this variant is usually named "Deficit Sudoku".
Richard published one in his sudoku Variant series in the portal with ID 0002D8 .
Please note: The German version of this page has changed. It is possible that this page does not contain the latest information.