Just for fun: Countdown numbers game solver

[dg.google.groups at thesamovar.net]

Arnaud and Terry,

Great solutions both of you! Much nicer than mine. I particularly like
Arnaud's latest one based on folding because it's so neat and
conceptually simple. For me, it's the closest so far to my goal of the
most elegant solution.

So anyone got an answer to which set of numbers gives the most targets
from 100 onwards say (or from 0 onwards)? Is Python up to the task?

A thought on that last one. Two ways to improve speed. First of all,
you don't need to rerun from scratch for each target. Secondly, you
can try multiple different sets of numbers at the same time by passing
numpy arrays instead of single values (although you have to give up
the commutativity and division by zero optimisations).

Dan Goodman