advent-of-code-2021 VS advent_of_code

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.

Again this year I am posting my reflections for solving all of these in Haskell https://github.com/mstksg/advent-of-code-2021/blob/master/reflections.md :)

Like every year, i have my haskell solutions and reflections every day here :) https://github.com/mstksg/advent-of-code-2021

Here's the relevant extract from my (recursive) solution. Full code on GitHub.

Like others, I used lcm. Here's an extract of the solution, omitting parsing and main(). Full solution on GitHub.

Solutions to parts 1 and 2 nearly identical and pretty much worked first time. Nothing clever here. This was far simpler than I thought it would be. I probably spent most time trying to think of a mathematical way of getting all points between p1 and p2. In the end, I just constructed two ranges. Full code here.

Full code on github.

The core of my solution below using numpy (because I'm learning it!). See github for full code.

Python 3 solution using numpy. I got held up because I assume (but know better) that numpy arrays are [x,y] instead of [row, col], which is [y,x].

Below is the new solution, which works for part 1 and 2. The full code is on GitHub.

These are the key functions. The whole code is on GitHub

Part 2 (extract shown below) was a matter of starting with the low points found in part 1 then recursively looking around for relevant points. Full code on GitHub

Code is on GitHub.