public class Solution
extends Object
1026 - Maximum Difference Between Node and Ancestor\.
Medium
Given the `root` of a binary tree, find the maximum value `v` for which there exist **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:** root = [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.
**Example 2:**
**Input:** root = [1,null,2,null,0,3]
**Output:** 3
**Constraints:**
* The number of nodes in the tree is in the range `[2, 5000]`.
* 0 <= Node.val <= 105