Given the root of a binary tree, find the largest subtree, which is also a Binary Search Tree (BST), where the largest means subtree has the largest number of nodes.
A Binary Search Tree (BST) is a tree in which all the nodes follow the below-mentioned properties:
- The left subtree values are less than the value of their parent (root) node's value.
- The right subtree values are greater than the value of their parent (root) node's value.
Note: A subtree must include all of its descendants.
10 / \ (5) 15 / \ \ (1) (8) 7 Input: root = [10,5,15,1,8,null,7] Output: 3 Explanation: The Largest BST Subtree in this case is the highlighted one. The return value is the subtree's size, which is 3.
Input: root = [4,2,7,2,3,5,null,2,null,null,null,null,null,1] Output: 2
- The number of nodes in the tree is in the range
-104 <= Node.val <= 104
Follow up: Can you figure out ways to solve it with
O(n) time complexity?