PROBLEM OF THE DAY : 24/07/2024 | Check for BST

Welcome to the daily solving of our PROBLEM OF THE DAY with Jay Dalsaniya We will discuss the entire problem step-by-step and work towards developing an optimized solution. This will not only help you brush up on your concepts of Binary Search Tree but also build up problem-solving skills.

Given the root of a binary tree. Check whether it is a BST or not.
Note: We are considering that BSTs can not contain duplicate Nodes.
A BST is defined as follows:

The left subtree of a node contains only nodes with keys less than the node's key.

The right subtree of a node contains only nodes with keys greater than the node's key.

Both the left and right subtrees must also be binary search trees.

Examples:

Input: 
    2 
  /    \ 
1      3
          \
           5
Output: true 
Explanation: The left subtree of every node contains smaller keys and right subtree of every node contains greater. Hence, the tree is a BST.

Give the problem a try before going through the video. All the best!!!
Problem Link: https://practice.geeksforgeeks.org/problems/check-for-bst/1