Thursday, March 11, 2021

The hard version of this sudoku seems to require A LOT of bifurcation, or techniques I am unaware of. The easier version is quite enjoyable, imo.


I was playing around with Supradoku and f-solver and created a puzzle that has a unique solution according to supradoku, but f-solver is unable to find it (on my computer, at least). I tried to solve it by hand, but quickly found that I needed to use a lot of bifurcation. I wouldn't be surprised if some sort of set equivalence or other advanced techniques can make it more manageable, though. 

Rules are standard anti-knight and thermometer rules, so squares that are a knight's move away from each other cannot hold the same digit, and digits on thermometers must increase from the bulb. you can try it at

Since I was having so much difficulty, I looked at Supradoku's given solution, then saw a couple places I could add thermometers to make a much more manageable puzzle (with the same solution). In my own testing, this version took me about an hour to solve and was very enjoyable.


You can play the easier version at

Monday, March 8, 2021

A sudoku with 42 "unique" solutions?

This sudoku has 42 "unique" solutions, 1 of which will be chosen by the solver at the beginning of the puzzle.

Rules: Standard sudoku rules apply. 

Digits cannot repeat in cages and the sum of the digits in a cage must sum to the number in the corner of the cage (If you know CTC's secret, those clues are unnecessary). 

Digits in thermometers increase from the bulb.

The digits 1 through 9 appear exactly once on each long diagonal.

To start the puzzle, pick any two numbers from 1, 3, 5, 6, 7, 8, 9 and put them into the highlighted dominos in the same order (for example, if r3c4 is 9 and r4c4 is 8, then r5c9 and r6c6 should both be 9 and r6c9 and r7c6 should both be 8). Now you should have a puzzle with a unique solution. 

Thanks to Supraduko and SudokuWiki, whose software was immensely helpful in building this, and to Cracking the Cryptic for renewing my interest in sudoku and introducing me to killer/thermo rulesets among others.