You are given the root of a Binary Search Tree (BST), convert it to a Greater Tree such that every key of the original BST is changed to the original key plus the sum of all keys greater than the original key in BST.
As a reminder, a binary search tree is a tree that satisfies these constraints:
Example 1:
Input: root = [10,9,15,4,null,12,19,2,5,11]
Output: [67,76,34,85,null,46,19,87,81,57]Example 2:
Input: root = [2,1,3]
Output: [5,6,3]Constraints:
0 <= The number of nodes in the tree <= 10,000.-10,000 <= Node.val <= 10,000root is guaranteed to be a valid binary search tree.