## README ¶

### 538. Convert BST to Greater Tree (Medium)

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 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.

**Note:** This question is the same as 1038: https://leetcode.com/problems/binary-search-tree-to-greater-sum-tree/

**Example 1:**

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]

**Example 2:**

Input:root = [0,null,1]Output:[1,null,1]

**Example 3:**

Input:root = [1,0,2]Output:[3,3,2]

**Example 4:**

Input:root = [3,2,4,1]Output:[7,9,4,10]

**Constraints:**

- The number of nodes in the tree is in the range
`[0, 10`

.^{4}] `-10`

^{4}<= Node.val <= 10^{4}- All the values in the tree are
**unique**. `root`

is guaranteed to be a valid binary search tree.

#### Related Topics

[Tree] [Depth-first Search] [Binary Search Tree] [Recursion]

## Documentation ¶

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