it is a constrained binary tree i.e insertion can occur only according to some conditions.
- all the left subtree nodes are smaller than the root node
- all the right subtree nodes are greater than the root node
- above two conditions is true for each node in the tree i.e left and right subtrees must also be BST
Insert in BST
- Insertion should be done that the constraints given above mustn’t be invalid after insertion of node.