Longest Univalue Path

Medium

Given the root of a binary tree, return the length of the longest path where every node on the path has the same value. The length is measured in edges. The path need not pass through the root.

Example 1

Input:  root = [5,4,5,1,1,null,5]
Output: 2

Example 2

Input:  root = [1,4,5,4,4,null,5]
Output: 2

Constraints

• 0 <= number of nodes <= 10^4
• -1000 <= Node.val <= 1000