# 226. Invert Binary Tree

## Easy

***

Given the `root` of a binary tree, invert the tree, and return _its root_.

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**Example 1:**

![](https://assets.leetcode.com/uploads/2021/03/14/invert1-tree.jpg)

```
Input: root = [4,2,7,1,3,6,9]
Output: [4,7,2,9,6,3,1]
```

**Example 2:**

![](https://assets.leetcode.com/uploads/2021/03/14/invert2-tree.jpg)

```
Input: root = [2,1,3]
Output: [2,3,1]
```

**Example 3:**

```
Input: root = []
Output: []
```

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**Constraints:**

* The number of nodes in the tree is in the range `[0, 100]`.
* `-100 <= Node.val <= 100`
