Problem: Validate Binary Search Tree
Explore how to validate whether a binary tree satisfies the binary search tree properties using recursion and range constraints. Learn to implement a helper function that checks node values against dynamic bounds, ensuring the entire tree maintains the BST order for both left and right subtrees. Gain insights into the time and space complexity of this recursive approach to build confidence in applying it to similar tree validation tasks.
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Statement
Given the root of a binary tree, determine whether it is a valid binary search tree (BST).
A valid BST satisfies the following properties:
The left subtree of every node contains only nodes with keys strictly less than that node’s key.
The right subtree of every node contains only nodes with keys strictly greater than that node’s key.
Both the left and right subtrees must themselves be valid binary search trees.
Return true if the given binary tree is a valid BST, and false otherwise.
Constraints:
The number of nodes in the tree is in the range
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