Merge two binary search trees?

Question

This was asked today at Amazon interview -

Given two Binary Trees (not BST). Each node of both trees has an integer value. Validate whether both trees have the same integers, there could be repetitive integers.

Example
Tree1:
5
1 6
5 4 3 6

Tree2:
1
3 4
6 5

Output
Identical integers

Sample C/C++/Java code would be helpful.

Answer 1

Method (Insert elements of first tree to second)
Take all elements of first BST one by one, and insert them into the second BST. Inserting an element to a self balancing BST takes Logn time (See this) where n is size of the BST. So time complexity of this method is Log(n) + Log(n+1) … Log(m+n-1). The value of this expression will be between mLogn and mLog(m+n-1). As an optimization, we can pick the smaller tree as first tree.