Advent of Code 2018 solutions in Kotlin
This is me trying to get to know Kotlin, I did previous years in Scala. I noticed that at the end, when revisiting my earlier solutions, I could clean them up quite a bit so at least I've learned something.
Initial setup copied from Todd Ginsberg who has a great repo with accompanying blog that you should definitely look at if you have not already.
Files you may find interesting:
Kotlin sequence block is very handy, I retrofitted one into Day 1 as well.
I managed to reduce the move method to a single breadth-first search with a little bit of extra administration.
Used the sort-of-normalized form of the input to solve that one with minimal means. No need to create a map of the dungeon.
I tried so many things here, my initial idea was to solve the problem at a coarser resolution and then repeatedly zoom in to find the exact point. Worked alright for my own input but for other inputs this fails. Then I tried some heuristic optimisation techniques which failed as well. Finally I saw someone who kept splitting a box into eight parts, tracking the one that overlaps with the most spheres. So simple that I should've thought of it, and efficient enough to work for all inputs that I saw.
I am used to the extremely consistent and well-designed Scala standard library and hopping over to Kotlin took a little getting used to. But the ability to create a little advent-of-code library made up for some of the hardship. The first time you notice you can re-use methods you put on certain classes is good fun.
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