Longest Consecutive Path in Binary Tree

Given a binary tree, return the length of the longest parent-to-child path whose values increase consecutively by 1. Follow-up: allow the path to extend in any direction through the tree, not only from parent to child. Requirements Input: the root of a binary tree. Base task: return the length of the longest path where each next node is a child of the previous node and child.val = parent.val + 1. The path direction is strictly parent → child in the base version. Follow-up: allow the path to extend in any direction through the tree, so a valid consecutive chain may pass through a node and continue into another branch. Notes In the base version, carry the current consecutive length while traversing downward and reset to 1 whenever the child is not exactly parent + 1. For the any-direction follow-up, track increasing and decreasing chain lengths at each node, then combine through the node when the left/right child values support a consecutive bridge. Clarify whether the answer is measured in nodes or edges before coding; Google candidates usually state node count. Preparation Write the parent-to-child traversal in under 10 minutes with a global best. Practice the bidirectional tree follow-up where each node returns two lengths upward. Dry-run single-node, duplicate-value, and split-branch cases before discussing complexity.