I made something (kinda) useful and put it on GitHub! Look look!
It's an implementation in C++ of the disjoint-set forest data structure. Building it for my specific purpose was fairly easy; abstracting it into template form and removing use of the Stanford library (namely, the HashMap) took AGES. I gained a lot of appreciation for how the Stanford libraries reduce C++ complexity so students can focus on learning objectives and not get lost in the esoteric details.
Any feedback on my implementation is very welcome.