Sad to think it’ll be over tomorrow 
Guess I’ll have to amuse myself in the rest of December by revisiting old puzzles I never solved!
Part 1 was super straightforward - this is a directed graph, and the two nodes are pretty close together.
For part 2, the nodes are not close together, they’re at opposite ends of the graph 
So I used a similar BFS approach to the puzzle with counting the timelines in the beam splitter (day 7) though this code ended up being a lot nicer! I split it into three parts - svr to fft, fft to dac, and then dac to out, multiplying the numbers together at the end.
https://github.com/sevenseacat/advent_of_code/blob/main/lib/y2025/day11.ex
Name ips average deviation median 99th %
day 11, part 1 321.81 3.11 ms ±5.50% 3.05 ms 3.57 ms
day 11, part 2 176.86 5.65 ms ±3.21% 5.61 ms 6.12 ms
