# Validate Binary Search Tree LeetCode Solution

## Validate Binary Search Tree LeetCode Solution :

Given the root of a binary tree, determine if it is a valid binary search tree (BST).

A valid 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.

## Validate Binary Search Tree LeetCode Solution :

### Constraints :

• The number of nodes in the tree is in the range [1, 104].

• -231 <= Node.val <= 231 – 1

## Approach for Validate Binary Search Tree LeetCode Solution : :

1. Start with the root node and an initial range covering negative infinity to positive infinity.

2. Recursively check each node:

• Ensure that the node’s value is within the current range (between the left and right bounds).
• Update the range for the left child (it becomes [left bound, current node’s value)) because all values in the left subtree must be less than the current node’s value.
• Update the range for the right child (it becomes (current node’s value, right bound]) because all values in the right subtree must be greater than the current node’s value.
3. Continue this process for all nodes in the tree.

4. If at any point a node’s value is not within the specified range, return false, indicating that the tree is not a valid BST.

5. If the entire tree is checked without any violations, return true, indicating that the tree is a valid BST.

### Related Banners

Get PrepInsta Prime & get Access to all 200+ courses offered by PrepInsta in One Subscription

## Get over 200+ course One Subscription

Courses like AI/ML, Cloud Computing, Ethical Hacking, C, C++, Java, Python, DSA (All Languages), Competitive Coding (All Languages), TCS, Infosys, Wipro, Amazon, DBMS, SQL and others