Double Counting [Duality]
(Published on 17. October 2024, 16:42 by timotab)
- Normal Sudoku rules apply: place the digits 1 to 9 in every row, column, and box, once each.
- A circle's neighbourhood includes the cell containing the circle, and any cell touching it (on an edge or corner). The digit in the circle is the number of cells in its neighbourhood that have the same odd-even parity as the circled digit.
- Digits in circles also indicate how many circles in the puzzle that contain that digit.
Solution code: column 8.
Last changed on on 1. November 2024, 15:04
Solved by hrhgln, Shuhua Milk, Snookerfan, SKORP17, lmdemasi, Zandi, sujoyku, DanishDynamite, GorgeousNicko, purpl, johncj, mercierus, casquefou, Kupais, Piff, Glasgow, ValentinL, eamondo, tjomi, Ashryn, ... Illuminated, unlogical, jklimp, geronimo92, The Book Wyrm, Leilalu222, asver, abadx, yttrio, NEWS, michaal94, talldrinkofwater, damasosos92, jgarber, pigeonsteps, AdamantChorus, kangaroo, MysticMan
Comments
on 7. September 2026, 07:42 by MysticMan
Lovely puzzle!
ps: Not sure if that was the intention of the title, but double counting is a really nice mathematical proof technique (and one of my favorites).
on 6. December 2025, 02:20 by damasosos92
Very smooth puzzle, thanks!
on 26. October 2024, 05:16 by timotab
fixed error in rules (on this page - puzzle itself was fine), and also simplified solve code
on 22. October 2024, 11:07 by cg24
this was my first time with this kind of ruleset, i liked it very much :) lovely puzzle
on 20. October 2024, 15:10 by thebriskt
Please stop requiring 18 digit solution codes, it's overkill and hostile to mobile users
