Vive la différence!
(Published on 8. October 2020, 20:00 by stephane.bura)
Normal Sudoku rules apply.
If a line is present in a cell, it indicates that the value of this cell is the absolute difference between its two neighbors in that direction.
For instance, 437 and 743 are valid neighbors if there is a line in the central cell.
The grid is toroidal, so r5c1 is the absolute difference between r5c2 and r5c9.
All the possible lines are given.
Solution code: Row 1, row 2
Comments
on 25. October 2025, 21:07 by rich_27
I think I kept messing up by inverting the ordering of a given sequence in my head, i.e. mentally moving the line one place by accident. The first couple of times I tried I broke the puzzle and didn't really have a good idea of why, but then this last time it just went really smoothly with no issues, weird!
Here's a sudokupad link: https://sudokupad.app/ckxepm1fl8
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Thanks!
I originally gave a higher difficulty to this puzzle because of the mental load generated by R5. But solvers have spoken :)
on 22. December 2021, 22:39 by pipedreambomb
I really struggled initially (hint: lines aren't always about subtracting from a digit you already have; sometimes you need to add to it), but I'm so glad I persisted because this is an astonishing puzzle. I was just in awe once I got the hang of it.
I feel like it could be a whole genre of sudoku like German Whispers, where you slowly get better at it and know what to look for and which numbers are hard to put on lines.
Can't believe it's only had 28 solves in over a year. People should know about this puzzle!
on 13. October 2020, 12:56 by henrypijames
How can this one be only 2 stars in difficulty?
