Solution (leetcode-in-java 1.21 API)

java.lang.Object
- g1301_1400.s1373_maximum_sum_bst_in_binary_tree.Solution

```
public class Solution
extends Object
```
1373 - Maximum Sum BST in Binary Tree.
Hard

Given a binary tree root, return the maximum sum of all keys of any sub-tree which is also a Binary Search Tree (BST).

Assume a 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.
Example 1:

Input: root = [1,4,3,2,4,2,5,null,null,null,null,null,null,4,6]

Output: 20

Explanation: Maximum sum in a valid Binary search tree is obtained in root node with key equal to 3.

Example 2:

Input: root = [4,3,null,1,2]

Output: 2

Explanation: Maximum sum in a valid Binary search tree is obtained in a single root node with key equal to 2.

Example 3:

Input: root = [-4,-2,-5]

Output: 0

Explanation: All values are negatives. Return an empty BST.

Constraints:
- The number of nodes in the tree is in the range [1, 4 * 10⁴].
- -4 * 10⁴ <= Node.val <= 4 * 10⁴

- Constructor Summary
  
  Constructors
  Constructor Description
  
  Solution()
- Method Summary
  
  All Methods Instance Methods Concrete Methods
  Modifier and Type Method Description
  
  int maxSumBST(TreeNode root)
  - Methods inherited from class java.lang.Object
    clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail
- Solution
```
public Solution()
```

Method Detail

maxSumBST

public int maxSumBST(TreeNode root)