Given a set of n distinct elements and an unlabeled binary tree of n nodes. In how many ways we can populate the tree with the given set so that it becomes a binary search tree?
How exactly do you take the current elements into account to find an appropriate place for the new element?
The problem statement does not make much sense to me. If a tree is given, then each labeling, viewed as a binary search tree, corresponds to one and only one ordering of the labels (i.e., elements).