# 226.E 翻转二叉树

> Problem: [226. 翻转二叉树](https://leetcode.cn/problems/invert-binary-tree/description/)

## 思路

递归法。先递归翻转左右子树，然后交换根节点的左右子树。

## Code

```go
/**
 * Definition for a binary tree node.
 * type TreeNode struct {
 *     Val int
 *     Left *TreeNode
 *     Right *TreeNode
 * }
 */
func invertTree(root *TreeNode) *TreeNode {
	if root == nil {
		return root
	}

	left := invertTree(root.Left)
	right := invertTree(root.Right)
	root.Left = right
	root.Right = left
	return root
}
```