Thanks for this kata.

I think the test has a serious deficiency: it does not check if the solution contains the smallest possible numbers, although this condition is stated in the problem description. Please modify the test or the description.

The check_list test function always returns True if one of the arrays is empty.

There seems to be an issue with the test case in Python, when I try and just return the passed variable in the function to see what datatype needs returned, it says there is something wrong with the test case, I might just be stupid but I don't think that is supposed to happen.

Hello! Try writing solutions for smaller arrays on paper (Note that there are many solutions). Some of them will help you find the pattern

I can't even solve this with pen and paper. Am I stupid or is this a very difficult one?
Any hints to get started?

Approved

I forked the kata with a more efficient solution verification method. What with all the talk about performance in the discourse below, I figured a good way to start was to eliminate the O(n²) operation that had to be performed on every test.

Maybe someone can take a look and see whether I missed anything.

I would specify in the description the intended time complexity, and also add a tag: performance

I hope users will revote knowing these performance constraints

did it just before I went to sleep, not thinking too much...

This is a very naughty solution ;-) Are you sure you're writing in Python?

Perhaps you can just use my solution and demand an O(n) solution.

Of course.

You can use the one I forked, more neat.

It is, thanks!