Maximum Difference Between Node and Ancestor

Description

Given the root of a binary tree, find the maximum value V for which there exists different nodes A and B where V = |A.val - B.val| and A is an ancestor of B.

(A node A is an ancestor of B if either: any child of A is equal to B, or any child of A is an ancestor of B.)

Example 1:

Input: [8,3,10,1,6,null,14,null,null,4,7,13]
Output: 7
Explanation: 
We have various ancestor-node differences, some of which are given below :
|8 - 3| = 5
|3 - 7| = 4
|8 - 1| = 7
|10 - 13| = 3
Among all possible differences, the maximum value of 7 is obtained by |8 - 1| = 7.

Note:

The number of nodes in the tree is between 2 and 5000.
Each node will have value between 0 and 100000.

Solution(javascript)


const maxAncestorDiff = function (root) {
  let result = 0
  const aux = (node, currentMax, currentMin) => {
    if (!node) {
      result = Math.max(Math.abs(currentMax - currentMin), result)
      return
    }
    const max = currentMax === undefined ? node.val : Math.max(currentMax, node.val)
    const min = currentMin === undefined ? node.val : Math.min(currentMin, node.val)
    aux(node.left, max, min)
    aux(node.right, max, min)
  }
  aux(root)
  return result
}