>
>     # BUG:  [0, 1], [1, 0] => 6  # there are only two edges
> #     10.times do |count|
> #       graph_down_and_back(count)
> #       assert_equal(count * 2, @graph.num_edges)
> #       0.upto(count) do |i|
> #         assert_equal( @graph.num_edges,
> #                        
> @graph.max_length_of_simple_path_including_node(i) )
> #       end
> #     end
>   end
>
I got this result with [1,2], [2,1], the 6 really threw me off - was I 
not understanding the concepts of digraph (so back to the web to check 
my knowledge), or was it one of those bugs referred to in the quiz...?

Nice to know that someone else thought that this was a bug - I couldn't 
get why 1=>2=>1 would have 6 edges/vertices :)

Thanks for posting the black box stuff James, I've been wondering about 
those 6 vertices since yesterday!

Kev