Here are several years of old AoC problems I've solved, but have just been sitting around on my hard drive for ages.
This is a casual repository. Expect healthy doses of nonsense and profanity in code comments, which I'm not going to bother censoring in order to preserve the spirit and soul of the repository. There are also a handful of random visualizations I made for fun.
Almost all of these were solved without cheating (i.e. having to look at someone else's solution), but there were a handful—around 1 per year—involving some obscure algorithm, or branch of mathematics (usually number theory) that I'm not familiar with, and I eventually gave up on. Chances are there's an angry comment in the code somewhere that reflects each of these instances.
Not all solutions will work on every input, since these were typically only tested on my input. Some solutions were overengineered in order to handle "big boy" inputs from /g/, which tend to be several orders of magnitude more computationally expensive than any official inputs, and thus require upgrading to a non-naive algorithm to solve.
Please note that I have zero formal education in anything pertaining to Computer Science, so expect weird implementations from time to time.