whilst building a tree, build a hash that maps a full dir path to a tree-node.
can then immediately jump to a particular node, do the combine and then recurse back up.
this should be faster than starting at the top and descending down and doing a hash lookup at each level.
whilst building a tree, build a hash that maps a full dir path to a tree-node. can then immediately jump to a particular node, do the combine and then recurse back up. this should be faster than starting at the top and descending down and doing a hash lookup at each level.