Toroidal anti-knight sudoku
(Published on 1. May 2020, 11:12 by Shinya)
a nice little (and not too difficult) puzzle from me.
Place the digits 1 to 9 in the grid, so that every number appears in each row, column, and bold shape exactly once. Identical digits must not be placed exactly one knight's move apart. The grid is toroidal, i.e. opposite boundaries of the grid are connected (e.g. R1C1 is connected to R9C1 and R1C9). This applies both for the bold shapes, and the knight's moves (e.g. R1C1 and R8C9 must not contain the same number).
I think speed-solving this by bifurcating can be done pretty quickly, but don't miss out on the logic ;-)
Have fun!
Solution code: Row 1, column 1
Comments
on 2. May 2020, 14:32 by r45
Sehr schön mit einer Logik, die man sich erst einmal erarbeiten muss. Hat viel Spaß gemacht, herzlichen Dank.
on 1. May 2020, 21:56 by zhergan
Very nice design. Thanks:)
on 1. May 2020, 12:43 by Ours brun
@geronimo92 Read "connected" as "neighbours" in this sentence. It just means that they touch each other, not that they are part of the same region. As for R1C1 and R8C9, see R8C9 as being one cell to the left and two cells to the top of R1C1, hence a "toroidal knight move" away.
on 1. May 2020, 12:39 by Shinya
@geronimo92
That is the toroidal part. Maybe it is easiest if you check in the puzzle wiki for toroidal sudoku, there is an detailed example.
But in short: All geometry in this puzzle is rolling over to the other side. So all cells in row 9 are connected to all cells in row 1, and all cells in column 1 are considered adjacent to all cells of column 9.
on 1. May 2020, 12:33 by geronimo92
Excuse me just can you explain how R1C1 can be connected with R9C1 and R1C9 ?? (i really dont see how !!) and how R8C9 can be a knight's move from R1C1 too????
