Very cool kata, kudos to the author g964! I learnt so much solving it, had no idea about backtracking and how it works, went into rabbit hole of learning for a couple of days and was able to go back and solve it with new knowledge. Exactly the reason I love this site so much, very satisfying. Thanks!

Because in real cases the task may change to "divide by 6 if it's even and multiply by 10 if it's not". You would have to rewrite the whole logic of your function. If you had simple if/else then you just change a couple of numbers here and there.
Also, if/else is more readable and explicit.
Again, it's clever, but not the 'best' pracitce.

That is very cool solution. I wish I guessed it

Damn this is clever. I wonder if I'm too old and dumb to find solutions like that :/

Could you elaborate for us slower types, please?

Damn this is cool

You're totally right, Chrono79!
I completely overlooked empty lists, thank you for helping me

Any solution with list comprehension doesn't work even for built in test case.
I don't understand why is this happening, because in test case the list is not empty. I generate proper list, it prints it out correctly, but it won't work for np.lcm.reduce even though it should.

np.lcm.reduce([i[1] for i in lst])
numpy.core._exceptions._UFuncNoLoopError: ufunc 'lcm' did not contain a loop with signature matching types (None, <class 'numpy.dtype[float64]'>) -> None

Python. I am not getting this error in my IDE.

If I write it as np.lcm.reduce([2. 3, 4]) it works perfectly.
I believe there's an issue of some kind. How does it work for given list and not working with simplest list comprehension?

Thanks, I got it because of your explanation

I don't get it :|

Fun kata, had fun, thanks

Cool kata, made me think. Took a couple of tries, but was very enjoyable. Thanks

I broke my head trying to wrap it around this generator. To understand it easier consider writing it like this:

[number for subarray in array for number in subarray]

Still not easy though :|