aoc-2021

Advent of Code 2021 with Rust.

To build and run the project

This project uses cargo-aoc. More detailed instructions can be found at that project's README file.

1. Create an account at adventofcode.com
2. Get the value for your session cookie and configure cargo-aoc:

cargo aoc credentials -s TOKEN

3. Build and run the code with:

cargo aoc

Log

Day 1

I found out about the slice::windows method in Rust, which enables both parts of today's puzzle to be solved with functional programming.

For part 1, it's as simple as iterating the entries with a window of size 2, and then folding the result:

measurements.windows(2).fold(0, |total, window| {
  total + if window[1] > window[0] { 1 } else { 0 }
})

For part2 we need to first create triplets (which are windows of size 3), and then iterate over the list of triplets as if they were windows of size 2, to be able to access both the current triplet and the previous one:

let triplets: Vec<&[u64]> = measurements.windows(3).collect();
triplets.windows(2).fold(0, |total, window| {
  // ...
})