CareerCup

do the inorder traversal the second element will be the second smallest
check this number with the number returned by the given function

i agree with king kong upto 5.
7 and 8, u mean u will send an invalid binary search tree?

i would like to add 2 more cases
3.1-> an inbalanced binary search tree with a left subtree being empty and all nodes being on the right tree.

3.2-> two duplicate minimums

There is a general problem of finding the kth smallest element in a tree. A classic kth order statistics problem which can be solved by Augmenting datastructure[using Redblack trees]. THis operation of finding the RANK can be found in Log(N) time.

1. null tree
2. tree with 1 node
3. BST tree with 2 nodes
4. BST with duplicate minimums

i guess they are asking about testing the function, not finding the 2nd minimum, am i right?

1) Dont give it a BST
2) Let BST be null
3) Let there be only 1 element
4) Let there be 2 elements (valid case)
5) let there be n elements where n > 2
6) let there be numbers where 2nd smallest is parent of the smallest
7) let there be numbers wehre 2nd smallest is child of smallest
8) let there be numbers where 2nd smallest is child of child of smallest