Here is my solution.

I got top 80-90! Here is the meat of my solution.

I specifically designed my intcode interpreter to allow rapid extension of it, I even spent an hour cleaning it up the other day, seems like that paid off.

It’s pretty cool to see how well a recursive interpreter of a self-modifying memory/code VM actually ends up working with immutable memory. Very fun.

I would also be curious about the timings people got on the second part. Mine was 3.860 seconds (timed from the shell).

Nothing too exciting in my code here. My intcode computer has overall been a bit of a mess due to not going back and cleaning it up.

This problem really showed some issues in how I had implicit rules baked into my code. I was not putting arg 3 through any type of mode checking, because it was always itself previously. That bit me hard today, and I had to spend a ton of time debugging why my stuff wasn’t working.

This is my solution. So far I strived to keep the code clean, and this payed off, b/c the changes to the machine code were minimal. I finally extracted Intcode interpreter into a separate module, but I still keep that module code in the same file as the solution, so others can easily read the entire solution from a single file. As for the perf, the 2nd part takes about 500ms on my machine.

Thank you guys!
Updated to a Map data structure, and it does all the difference!

CleanShot 2019-12-09 at 17.16.02@2x1118×194 17.1 KB