# 0549. Binary Tree Longest Consecutive Sequence II

<https://leetcode.com/problems/binary-tree-longest-consecutive-sequence-ii>

## Description

Given the `root` of a binary tree, return *the length of the longest consecutive path in the tree*.

A consecutive path is a path where the values of the consecutive nodes in the path differ by one. This path can be either increasing or decreasing.

* For example, `[1,2,3,4]` and `[4,3,2,1]` are both considered valid, but the path `[1,2,4,3]` is not valid.

On the other hand, the path can be in the child-Parent-child order, where not necessarily be parent-child order.

**Example 1:**

![](https://assets.leetcode.com/uploads/2021/03/14/consec2-1-tree.jpg)

```
**Input:** root = [1,2,3]
**Output:** 2
**Explanation:** The longest consecutive path is [1, 2] or [2, 1].
```

**Example 2:**

![](https://assets.leetcode.com/uploads/2021/03/14/consec2-2-tree.jpg)

```
**Input:** root = [2,1,3]
**Output:** 3
**Explanation:** The longest consecutive path is [1, 2, 3] or [3, 2, 1].
```

**Constraints:**

* The number of nodes in the tree is in the range `[1, 3 * 104]`.
* `-3 * 104 <= Node.val <= 3 * 104`

## ac

```java
```