I am curious to know... which challenges were hard for tou?

I found 2020 to be mostly straightforward. for me, the trickiest for that year were: day20 - I had a few bugs that didn’t show up in test cases for part1 and that caused problems in part2 day23 - I had to learn more about type annotations to get my solution to run in seconds instead of days. 🙂

kool @AC I am still on 20, and just saw the light at the end of the tunnel - fun stuff…

I need to get back to this year, I only got up to day 16 before I had too much stuff to do with family that I couldn't find time to work on it. But up to day 16 it was all fairly straight forward. Apart from day 14, I couldn't get a working solution to part 2.