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# 1740. Find Distance in a Binary Tree

<https://leetcode.com/problems/find-distance-in-a-binary-tree>

## Description

Given the root of a binary tree and two integers `p` and `q`, return *the **distance** between the nodes of value* `p` *and value* `q` *in the tree*.

The **distance** between two nodes is the number of edges on the path from one to the other.

**Example 1:**

![](https://assets.leetcode.com/uploads/2018/12/14/binarytree.png)

```
**Input:** root = [3,5,1,6,2,0,8,null,null,7,4], p = 5, q = 0
**Output:** 3
**Explanation:** There are 3 edges between 5 and 0: 5-3-1-0.
```

**Example 2:**

![](https://assets.leetcode.com/uploads/2018/12/14/binarytree.png)

```
**Input:** root = [3,5,1,6,2,0,8,null,null,7,4], p = 5, q = 7
**Output:** 2
**Explanation:** There are 2 edges between 5 and 7: 5-2-7.
```

**Example 3:**

![](https://assets.leetcode.com/uploads/2018/12/14/binarytree.png)

```
**Input:** root = [3,5,1,6,2,0,8,null,null,7,4], p = 5, q = 5
**Output:** 0
**Explanation:** The distance between a node and itself is 0.
```

**Constraints:**

* The number of nodes in the tree is in the range `[1, 104]`.
* `0 <= Node.val <= 109`
* All `Node.val` are **unique**.
* `p` and `q` are values in the tree.

## ac

```java
```