Next Greater Number BST

Given a BST node, return the node which has value just greater than the given node.

Example:

Given the tree

               100
              /   \
            98    102
           /  \
         96    99
          \
           97

Given 97, you should return the node corresponding to 98 as thats the value just greater than 97 in the tree.
If there are no successor in the tree ( the value is the largest in the tree, return NULL).

Using recursion is not allowed.

Assume that the value is always present in the tree.

PROBLEM APPROACH:

Complete solution in the hint.

NOTE: You only need to implement the given function. Do not read input, instead use the arguments to the function. Do not print the output, instead return values as specified. Still have a question? Checkout Sample Codes for more details.