adventofcode VS advent-of-code-2020

This lets you cut out the relatively expensive fcount.remove(0) operation, and each loop is basically one addition and a few assignments. Full solution here.

Code

Your solution is pretty much exactly the super concise version of my definitely over-engineered solution.

You can see the code here

Here's my solution

Your solution looks remarkably similar to my Rust solution which solves both parts in 1.6s on the cheap NUC I use as my coding workstation.

It's in Rust, so I'm not sure how readable you'll find it, but in case it helps, you can see the code here.

I found a single crate with a bunch of binaries worked well. It let me use a shared library easily. You can see my crate organization here if that's helpful.

You can see my code here in case it helps.

It can. I did almost all the days from last year in Prolog (https://github.com/aarroyoc/advent-of-code-2020) so you can take a look. The most important thing is understand DCGs so you can use the pure input or pio library to read the data in a Prolog way. That library is already included in SWI or Scryer.