ntree.aiValidate Binary Search Tree
Validate Binary Search Tree
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Given the root of a binary tree, return true if it is a valid binary search tree.
A binary tree is a valid binary search tree if for every node:
- every value in its left subtree is less than the node value
- every value in its right subtree is greater than the node value
Example 1:
5
3
2
4
8
Input: root = [5, 3, 8, 2, 4]
Output: true
Example 2:
5
4
6
3
7
Input: root = [5, 4, 6, null, null, 3, 7]
Output: false
Explanation: 3 is in the right subtree of 5, so it has to be greater than 5.
Constraints:
1 <= the number of nodes in the tree <= 10^4-2^31 <= Node.val <= 2^31 - 1
# Definitions:# class TreeNode:# def __init__(self, val=0, left=None, right=None, parent=None):# self.val = val# self.left = left# self.right = right# self.parent = parent def isValidBST(root: TreeNode) -> bool: pass Press Visualise to step through your code.