On 17 Jul 2014, at 12:52, Drew Neil <andrew.jr.neil at gmail.com> wrote: > I recently set a challenge for Tom Stuart then recorded him as he solved the problem. And if anyone's interested, I wrote up some more detail (mostly on the "Ruby functional programming" side of things) on my blog: http://codon.com/notes-on-counting-tree-nodes Cheers, -Tom