[bnprks]

> Other tasks required studying the input data

I also felt there were more problems than usual this year that could not easily be solved without looking at the input for special cases not alluded to in the problem descriptions. (As someone who has solved all 25 for the past 3 years).

An extreme example was this year's day 20 circuit-simulating problem, which was made far easier by having the given circuit split up into a few independent chunks that are only connected at the start + end. (I suspect it might be NP-complete without this feature)

It's a slightly different kind of problem solving to think "what makes this particular input easier than the general version of this problem", and one that I'd naively assume LLMs are less skilled at.

[smokel]

There have been quite a few of these in the past. Some of the 2018 problems (e.g. day 21 [1]) required quite a lot of reverse engineering of programs in a custom instruction set.

[1] https://adventofcode.com/2018/day/21