[Not Invented Here Syndrome] is something I definitely don't have. I'm a bit of a hoarder, a magpie maybe, collecting shiny things. When I encounter a seemingly useful piece of code on the Internet I would download it and dump it into my downloads directory. I've probably got gigabytes of the stuff.
As much as I worry about diminishing skills, (low + high) >>> 1 is a good example for what not to know. It’s a recipe for a classic overflow bug, not beautiful in any way, and one thing I unlearned when I stopped low-level coding in C.
It was the Ruby natural sort on this page that prompted me to write a generic C++ version. It took me a couple of hours, most of which was learning to use the Boost.Regex iterators.