aoc2020 VS aoc

I've done every year in Haskell (2015 2016 2017 2018 2019 2020 2021), and so have several other people such as /u/glguy. I don't see if /u/mstksg has anything published for 2015 but they've done 2016 2017 2018 2019 2020 2021 along with some pretty good writeups, I recommend checking those out.

I benchmarked all 25 days in 4 languages (using GitHub Actions, which performs worse than my local dev setup, but feels more fair for reproducibility). Can't get any pretty animated output, though.

Rust

Kotlin

Rust

Rust

Rust

Rust

It's not compiled in release mode, as seen here. /u/tom_collier2002 add the flag -C opt-level=3

The solution I used to get the correct answer for day 23 was almost exactly what you described (I used an array instead of a hash table for the fast look up). However, a friend of mine used the "array as a linked list" approach that initially made no sense to me. So I spent an hour implementing it as a way to wrap my head around it. The surprising (to me) result was not only was the new solution 3x as fast as the original (11 seconds vs 35 seconds), but also used only 20% of the memory (45 MB RSS vs 236 MB RSS)!