Binary Search Tree to Greater Sum Tree
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 the 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.
Return the root of the converted Greater Tree.
Note: This question is the same as 538: https://leetcode.com/problems/convert-bst-to-greater-tree/
Example 1
4 -> 30
/ \ / \
1 6 36 21
/ \ / \ / \ / \
0 2 5 7 36 35 26 15
\ \ \ \
3 8 33 8Input
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 is replaced by its original value plus the sum of all original node values greater than it, producing the shown Greater Tree.
Example 2
0 1
\ -> \
1 1Input
root = [0,null,1]Output
[1,null,1]The node with value 0 gains the greater value 1, while the node with value 1 remains unchanged.
Constraints
- The number of nodes in the tree is in the range
[1, 100]. 0 <= Node.val <= 100- All the values in the tree are unique.