Bitsum Lines
(Published on 29. November 2025, 13:26 by RockyRoer)
The Rules:
- [Sudoku]Normal sudoku rules apply. Fill every row, column, and 3x3 box with the digits from 1 to 9 once each.
- [Binary Sum Lines] The digits along a line may repeat if sudoku rules apply. The sum of the digits on a line is equal to the binary sum of the line. A binary sum converts odd digits on the line to 1's and even digits to 0's, and then finds the value of the binary number read in the order of the arrow (from most significant bit down to least significant bit).
- Example: If the digits along a line were 5, 2, 6, 9, 8, 7, they would sum to 37, and the bit sum would be 100101 which is 1x32 + 0x16+ 0x8 + 1x4 + 0x2 + 1x1 = 37.
The Puzzle:
Try it on Sven's sudoku pad with helpful bit markers or without.
Solution code: Column 7
Comments
on 29. December 2025, 01:28 by damo_89
Mind bending in all the best ways
on 30. November 2025, 15:12 by Qodec
What a beauty! Thanks very much!
on 30. November 2025, 01:33 by RockyRoer
Fixed link with bit markers to include row 8.
on 30. November 2025, 01:28 by zeniko
I appreciate the labeled version and indeed used it after messing it up the first time. Sadly, I‘ve messed it up again with the r8-arrow for which the labels are missing - turns out, the puzzle would also be solvable with that arrow reversed… No worries, though, I still enjoyed the solve(s).
Reply: Ha! oops - didn't mean to leave that out. I laugh because earlier drafts of this puzzle did intentionally leave some arrows ambiguous, and row 8 specifically had been one that stayed ambiguous for a long time - but in the end I needed it, and I decided just to directionalize all of them. I fixed the link now.
on 29. November 2025, 22:24 by zeniko
Beautifully set. The trickiest thing was remembering, that arrows point to the LSB (reading order) and not the MSB (magnitude order), which I‘m apparently more used to. Thanks for sharing.
Reply: thanks for solving! For future solvers, there is a version with the bits labeled if you think you might mix up the direction of the lines
on 29. November 2025, 16:11 by Franjo
The master of arithmetic sudoku did it again! Though not easy solving this gem was a great pleasure and so satisfying. Thank you very much for creating and sharing another beautiful math-puzzle.
