Validate BST
You are given the root of a binary tree. Your task is to determine whether it is a valid Binary Search Tree (BST).
A BST is considered valid if, for every node:
- All values in its left subtree are strictly smaller than the node's value.
- All values in its right subtree are strictly greater than the node's value.
- Both the left and right subtrees must also be valid BSTs.
Return true if the tree satisfies all BST properties; otherwise, return false.
Input: root = [2,1,3]
Output: true
Explanation: Every node satisfies the Binary Search Tree property.
Input: root = [5,1,4,null,null,3,6]
Output: false
Explanation: The node with value 3 is in the right subtree of 5 but is smaller than 5, violating the BST property.
Input: root = []
Output: true
Explanation: An empty tree is considered a valid Binary Search Tree.
- 0 = Number of nodes = 105
- -10? = Node.data = 10?
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true
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true