Put in each row, in each column and in each 3x3 block the number from 1 to 9. In addition the eight close knight move cells must not contain consecutive numbers.
In case you prefer to solve the puzzle with more logical methods than by trial and error etc, you have to apply three advanced methods one after the other to solve the bottleneck of the puzzle. The first two steps are special cases of forcing chain:
Solution code: The first and the ninth row.
on 18. July 2023, 07:06 by uvo_mod
Added Sudoku tag.
on 28. November 2014, 16:50 by marcmees
very hard but rewarding.
on 13. April 2012, 17:16 by Richard
Schwere geburt, aber schoen konstruiert!
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