# 1123. Lowest Common Ancestor of Deepest Leaves

<https://leetcode.com/problems/lowest-common-ancestor-of-deepest-leaves>

## Description

Given the `root` of a binary tree, return *the lowest common ancestor of its deepest leaves*.

Recall that:

* The node of a binary tree is a leaf if and only if it has no children
* The depth of the root of the tree is `0`. if the depth of a node is `d`, the depth of each of its children is `d + 1`.
* The lowest common ancestor of a set `S` of nodes, is the node `A` with the largest depth such that every node in `S` is in the subtree with root `A`.

**Note:** This question is the same as 865: <https://leetcode.com/problems/smallest-subtree-with-all-the-deepest-nodes/>

**Example 1:**

![](https://s3-lc-upload.s3.amazonaws.com/uploads/2018/07/01/sketch1.png)

```
**Input:** root = [3,5,1,6,2,0,8,null,null,7,4]
**Output:** [2,7,4]
**Explanation:** We return the node with value 2, colored in yellow in the diagram.
The nodes coloured in blue are the deepest leaf-nodes of the tree.
Note that nodes 6, 0, and 8 are also leaf nodes, but the depth of them is 2, but the depth of nodes 7 and 4 is 3.
```

**Example 2:**

```
**Input:** root = [1]
**Output:** [1]
**Explanation:** The root is the deepest node in the tree, and it's the lca of itself.
```

**Example 3:**

```
**Input:** root = [0,1,3,null,2]
**Output:** [2]
**Explanation:** The deepest leaf node in the tree is 2, the lca of one node is itself.
```

**Constraints:**

* The number of nodes in the tree will be in the range `[1, 1000]`.
* `0 <= Node.val <= 1000`
* The values of the nodes in the tree are **unique**.

## ac

```java
```