98. Validate Binary Search Tree

[LeetCode] 98. Validate Binary Search Tree

98. Validate Binary Search Tree Medium 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. E..