AdventOfCode2020 VS AdventOfCode2021

I learned Zig first from the official guide at https://ziglang.org/learn/getting-started/, then from https://ziglearn.org/. I also used Zig to go through https://adventofcode.com/2020, which more about solving given tasks. At certain point you will be ready to read source code of Zig's std library in place for documentation.

2020 in Rust

Link to full solution

Phew, almost 2 hours of intense coding. This was an incredibly difficult day. Got flashbacks to day 20 of last year.

This is the seventh year puzzles, if you want to check out previous years take a look at: 2015, 2016, 2017, 2018, 2019, 2020

It actually was on day 19, it's just that puzzle #13 was the 19th puzzle given out [1]. I'm not sure why the numbers didn't come in order last year.

[1]: https://adventofcode.com/2020 shows the number order

I find that the "advent of code" project always has some nice challenges and you can access the previous years like https://adventofcode.com/2020. They tend to get complex and/or complicated quickly, but usually the first few are easy enogh, while sill giving you a challenge to learn something new.

https://adventofcode.com/2020 gives you well defined, deterministic problems that can be solved in a variety of ways. I'm loving it.

One important thing to note is that all numbers in the input are positive. Since they are all positive it can be solved quite easily in linear time, O(n), and O(1) memory complexity. See algorithm here. I used this algorithm in my Rust solution.

I found this repository which solves the problem by having a src/main.rs file which basically calls cargo run --release {day} and parses the output to extract the time each day took, but I don't find this very satisfactory. I'd prefer to have everything compiled into the same executable, without having to run external commands.

Try to do old advent of code https://adventofcode.com/2015 .. https://adventofcode.com/2021 there is 7 years worth of exercises. Try doing this upcoming one, but don't be discouraged if you cant keep up... If you manage to make the leader board at some point it might be your ticket to the US if that is something you want to do.

That's how I structured my solutions for Avent of Code in Rust, see here: https://github.com/AxlLind/AdventOfCode2021

My Rust solution runs in about 150ms, using just a standard Dijkstra implementation with nothing special like prioritizing moves like you propose.

2021 in Rust