omg I'm not sure I could have figured that out....
let me try for a larger number, like 12.

The description clearly says:

Find out how many unique products have each of the Producer.

And that's exactly why you do use the pair unique_products and producer in the result!

Welp, for me tests say 7 should equal 3. :| Python

Kacpers hint is the key ;-)

Waiting for the effect takes 30 minutes. Taking a pill takes no time.

It doesn't make sense for me. He has 35 minutes, so why he can take four pills?

Would you elaborate?

That seems nonsensical to me. Haskell is lazy, so the head function should only evaluate the first element of the list. For example I can write something like head ([2..] ++ [1]), and it doesn't seem too slow.

Though it may look cool, it adds O(number of factors of n) running time overhead (whereas empty-list check is a single operation).

Avoid ++ing at the end if you want a fast-running program.

Not hard to do by hand, just eta conversion and infix <-> prefix notation.

Definitely not a best practice in terms of code clarity though! :D

Thank you! It's so satisfying to lay things out his way :)

it seems as though, the standard if should have been implemented like Data.Bool.Bool has been

Now it makes sense.

Having jars A B C D E F G H Andrzej can take pills A B C D first friend can take pills C D E F second friend can take pills A C E G

@KacperKoban can you give an answer to this question that is not hidden(spoiler)