Judy Arrays are really cool, and unlike most data structures, because they are insanely complicated. Similar data structures can actually be completely described in 10 minutes like linked-lists, AVL trees, red-black trees, or even something weird like union-find can be described in 10 minutes.
It sucks HP patented them: US6735595
Unfortunately, since nobody actually pays someone for patent royalties these days everyone avoids this data structure like the plague, because patents are a plague: whenever something is patented everyone avoids it and stays away from it even if its better than everything else, which Judy arrays seem to be.
Can’t wait for Nov 29, 2020 when this patent expires. Unless, of course, congress extends patent lifetime again, which used to be only 17 years.