I've posted my solution, along with a few words about my approach, at
<http://www.io.com/~jimm/rubyquiz/quiz60/>.

Jim
--
Jim Menard, jim.menard / gmail.com, jimm / io.com
http://www.io.com/~jimm
"Generics in Java are an apology for having collections of Objects, and are
somewhat like the puritan's suspicion that someone, somewhere, might be
enjoying themselves."
    -- Steven T Abell in comp.lang.smalltalk