Nice kata, though missing some test cases that would make it super difficult. By the end my code was not the most elegant, and would probably fail some additional test cases.

Really nice kata!

Too simple for even an 8 kyu, in my opinion.

Random tests added, thank you.

(Should be!) fixed now, thanks guys.

Thanks, I missed this section when fixing. Will update shortly. Thanks for the input!

Oopsie. Thanks guys!

Hi, I've tried to make it a bit more clear but let me know if it's still confusing and I can try rewrite it. It's a bit tricket to get your head around if you don't know the terms, I think, apologies!

Hm good spot - I will reduce some of these large test cases to be more forgiving.

Thanks!

Finding the easiest/quickest solution is part of the fun!

Aha, this is where the typo in the description comes from ;) It should be

X_1 = [6, 9, 21] # -> X_1[2] = X[2] - X[1] = 21 - 9

Also had this issue, took me 4 submissions for 100% passes, each time having 1-2 fails off by 0.01