how do you get to the amount of the combinations?
for l=4 there are more than 4 combinations:
(((xx)x)x)
((xx)(xx))
((x(xx))x)
(x((xx)x))
(x(x(xx)))

which one is faster though?

isn't this O(n^2)?
not sure why so many people say it is best practices.

when you're too lazy to remove the comment

i think its a bit overcomplicated

it is just one line

das klingt nach einer interessanten idee!!

weird how you got dislikes. i even had 7kyu challenges that are harder than this one. 6kyu - 7kyu sounds more accurate.
note even sure why some people struggle with this one because its really straight forward (no mathematical trick, no algorithmic trick, no performance issues).
maybe some people dont know how to play sudokus and have a hard time understanding this problem.

it's written in python. time complexity doesn't matter there ;)

at least it is faster than calculating all primes