This was incredibly cool and I had a really fun time with it. Uncomment the draw and sleep in Part2 to see the game play itself! Note that I'm not seeking around in the terminal window to make the drawing smooth, I'm just outputting each new frame as it happens, so there's some jitter, but it still looks great!
I messed around a bit with control codes to move the cursor around instead of the "draw the buffer over and over again" approach, and they work, mostly, but I'm sticking with this for now.
This one was an absolute beating for me. I am so bad at these sorts of problems. Ultimately I settled on a probably-not-ideal solution that crawls the graph with offsets of each variant of (+/-x,+/-y), marking nodes visited as we come across them so that we end up with a list of asteroids that we can see. Given that this is day 10, and knowing how bad I am at math, I'm assuming this is very far from the intended solution, but it works reasonably quickly and I managed to come up with it myself, so I'm not going to stress too much about it.
For asteroid destruction, the best method I could come up with for finding the correct order was to implement an entire Vector class and sort by angle, which worked, but again, I can't decide if it was the intended solution or not. I should start reusing past years' codebases so I don't have to keep building a utility library from scratch.