Also related to AoC earlier - does Kotlin have any circular linked list data type or would I just use any Java implementation that I've previously had? My instincts tell me no since most Kotlin collections are based upon the Java ones.

I just appended the first element to the end of the list and used

zipWithNext

on it.

LOOOOL I DID THIS TOO. It's not so helpful for the second part, though.

What second part?

reminder that there's also

windowed

now

There's two parts to every AoC problem.

I only noticed the "sum of matching digits one" and got my golden star, what's the other one?

It's the same idea, but it's a circular list that wraps all the way around, so you might need to go beyond the "first" digit so it's not enough to just append it again.

I'll check it out later. You can emulate circular lists with

list[index % list.size]

if that helps.

That's what I've been told. I need to sit down and try that.