advent2020 VS adventofcode

Thanks for the reading! It turns out I misremembered a bit and the real issue was it’s not possible to create a preallocated array of a certain size (in this case 30 million elements 😱), as each iteration you do a lookup and append to the list. I think I tried :array but looking at the code now I’m not sure how it would perform. I ended up using :ets. If you’re curious my code is actually pretty short for that day.

Part one went fairly fast, but spent quite some time on getting part two right. I settled on the approach of just iterating over the grid and using a boolean to see if I had to count elements or not. However, I had some issues figuring out when to swap, this post by /u/rogual helped me figure it out. After that I lost quite some time on an error that only occurred with my input, not with the example input. It turned out that my loop (which I take form my p1 solution) didn't include the start node, which caused all sorts of counting issues.

[Language: Elixir] https://github.com/mathsaey/adventofcode/blob/master/lib/2023/4.ex