[thethirdone]

I was doing a little of catching up on older problems to improve my speed to get on the leaderboard and I found that the fastest way to finish one problem was to use oeis.

After seeing the problem [0], I didn't immediately think to use oeis because the manhatten distance of a spiral is pretty easy to code or do by hand. The second stage has a harder sequence though. It prompted me to check oeis and I easily got the answer [2] within a minute of checking.

Looking back at the first stage, I found a sequence for it [1] and PARI/GP code i could run to answer the question. If I had used oeis immediately I would have a solution to both phases in 2 minutes which would be the fastest on the old leaderboard for the problem [3].

[0]:https://adventofcode.com/2017/day/3

[1]:https://oeis.org/A214526

[2]:https://oeis.org/A141481

[3]:https://adventofcode.com/2017/leaderboard/day/3

[loeg]

I had plenty of 20-20 hindsight about faster ways to have solved puzzles in the past. I don't know if I was ever #1 on any day on either star. I think I might've been top 10, on one star, of one day, once.