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Binary Search Tree to Greater Sum Tree | CodeTutor

Binary Search Tree to Greater Sum Tree

Medium

Trees DFS (Depth-First Search)Binary Tree Traversal

Problem

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:

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.

Constraints

1 <= number of nodes <= 100
0 <= Node.val <= 100
All values in the tree are unique

Examples

Input: root = [4,1,6,0,2,5,7,null,null,null,3,null,null,null,8]

Output: [30,36,21,36,35,26,15,null,null,null,33,null,null,null,8]

Each node's value becomes the sum of itself plus all nodes with greater values. For example, node 4 becomes 4+5+6+7+8=30.

Input: root = [0,null,1]

Output: [1,null,1]

Node 1 has no greater values so stays 1. Node 0 becomes 0+1=1.

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