LeetCode: Convert Bst To Greater Tree Solution

Approach

Reversed in-order traverse (right to left)

Implementation

1/**
2 * Definition for a binary tree node.
3 * function TreeNode(val, left, right) {
4 *     this.val = (val===undefined ? 0 : val)
5 *     this.left = (left===undefined ? null : left)
6 *     this.right = (right===undefined ? null : right)
7 * }
8 */
9/**
10 * @param {TreeNode} root
11 * @return {TreeNode}
12 */
13var convertBST = function (root) {
14  let sum = 0
15
16  const traverse = function (node) {
17    if (!node) {
18      return
19    }
20
21    traverse(node.right)
22    sum += node.val
23    node.val = sum
24    traverse(node.left)
25  }
26
27  traverse(root)
28  return root
29}