Comparing Nodes in a Tree
I have no idea whether this algorithm is old or new, or even whether there are more efficient alternatives. But for a long time now, I’ve had a geeky fondness for an orphan data structure. I call it an orphan because I could never see any way of using it. It was just one of those pretty things. If you’ve ever had a geeky fondness for a data structure, then you’re pretty weird too.