Leetcode 549. Binary Tree Longest Consecutive Sequence II

Find the length of the longest path in a binary tree where adjacent node values differ by exactly 1 (either increasing or decreasing), and the path may go up through a parent and down to a child (i.e., can combine increasing and decreasing segments through a node). This requires tree traversal to compute, for each node, the longest increasing and decreasing consecutive runs in its subtrees and combine them to get the global maximum.