in reply to Tree Structure Challenge

I'm not sure if I get the problem, the naive solution is to collect all nodes from each tree with successive ->Parent calls and to construct the difference with cut operations. (like deleting hash slices)

What am I missing?

If the goal is to have minimal numbers of operations, we'd need to know things like if all leaves have the same distance to root.

Cheers Rolf
(addicted to the Perl Programming Language and ☆☆☆☆ :)
Je suis Charlie!