I'd like to suggest a topic for an upcoming RubyQuiz:
http://page.mi.fu-berlin.de/~prechelt/phonecode/taskdescription.html
has the full description.

Why?

It's a problem (realistic enough to be worthwhile, but still short
enough) that's been used to assess the difference strengths of
C/C++/Java (initially), then Perl/Python/Tcl, and finally Lisp.  Doing
so showcases what each language has to offer.  A lot of analysis has
been done about how long it takes to implement solutions in each
language, and what each language brings to the table.

Ruby's unfortunately conspicuously absent from the list, which is a
shame.  I for one would really like to see how Rubyists handle this
problem, as well as perhaps highlight some things that Ruby might learn
from other languages.

One more thing: I'd ask that the RubyQuiz follow the initial task's
request that submitters also note how long they spent on it.