Advent of Code 2020 solved with Elixir
Advent of Code is back! Last year, I took a stab at it using Elixir, but only had the time and resources to solve a handful of the problems. This year I’ll try again.
I’ve used Elixir only a few times. The language’s bizarre elegance intrigues me; its lack of common programming features like for and while loops is offset by pattern-matching, pipelines, and immutability. I haven’t written enough Elixir code to become comfortable with these strange new tools, but they’re foreign enough to be interesting—and who knows what unknown unknowns are lurking beyond my horizon?
Anyway, I’m hoping that a month of occasional floundering with Elixir will expand my mental framework of what programming actually means (like Ruby, Clojure, and functional programming did). So, onward to the code:
Instructions
Assuming that Elixir is installed on your system:
-
Solving the day’s problem:
elixir day-01.exs -
Running tests:
elixir -r day-01.exs day-01-test.exs
What I Learned
Day 1:
There's no shame in stealing (code)! I implemented Part 1 using a simple, efficient algorithm that runs in O(n) time. But as usual, Part 2 switched things up just enough that my “simple” solution no longer felt like a good fit. So I threw caution/efficiency to the wind and just used combinations, as I should have done in Part 1 instead of getting sidetracked by premature optimization. As it turns out, Elixir doesn't natively support permutations and combinations like my good friend Ruby, but if someone else has written that code already (which is essentially just an implementation detail), why should I waste time reinventing the wheel?
Day 2:
Module nesting and scoping are really intuitive.