Anti-sudoku puzzle #3
(Published on 17. February 2020, 06:56 by Nylimb)
This is the opposite of a sudoku puzzle:
Put a number from 1 to 9 in each cell so that in each row, column, and 3x3 box no number occurs exactly once. I.e. if a number occurs at all, it must occur at least twice.
I think this is much harder than Anti-sudoku puzzle #2. But there is a logical path to the solution; it's not necessary to make multiple copies of the grid to try different possibilities.
I created most of the puzzle by hand, but used a computer program that I wrote to explore ways to finish it.
The puzzle is available on Penpa.
Solution code: Row 7 and column 5.
Comments
on 22. October 2020, 23:43 by Nylimb
Added Penpa link.
on 17. September 2020, 13:53 by cdwg2000
Video problem solving from Bilibili website: https://b23.tv/bwCo8o
@cdwg2000: Thanks for the link. I don't understand the language, but it was interesting to follow the logic anyway.
on 7. April 2020, 12:36 by pin7guin
Komisches Gefühl, so gegen die "normalen" Regeln zu lösen...
on 1. March 2020, 22:54 by Mesmer
I figured out the logic early, but, somehow I messed up everytime, and it took me the whole day to solve it. So, @Nylimb amazing job and fork you :)))
on 17. February 2020, 09:48 by Nylimb
Fixed a typo.
on 17. February 2020, 08:37 by cdwg2000
Yeah.
The puzzle can be done through a purely logical path.
