For a given binary tree find maximum binary search sub-tree

Question

For a given binary tree, find the largest subtree which is also binary search tree?

Example:

Input:

                   10
               /                


        

Answer 1

A binary search tree will give you a sorted result if you do a IN-ORDER Traversal. So, do an in-order traversal for the entire binary tree. The longest sorted sequence is your largest binary search sub tree.

• Do a inorder traversal of elements (VISIT LEFT, VISIT ROOT, VISIT RIGHT)
• While doing so, get the node data, compare whether the previous node data is lesser than the next data. If so, increment counter by 1. Store the start node.
• When the comparison fails, store the end node and reset counter to 0
• Store this information (counter,start,end) node in an array structure to later find which is having the maximum value and that will give you the longest binary search sub tree