# 226 Invert Binary Tree

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

Example 1:

``````      4                   4
/   \               /   \
2     7       =>    7     2
/  \   /  \         /  \   /  \
1    3 6    9       1    3 6    9

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

Example 2:

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

Example 3:

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

Constraints:

• The number of nodes in the tree is in the range `[0, 100]`.
• `-100 <= Node.val <= 100`
 `````` 1 2 3 4 5 6 7 8 9 10 11 12 13 14 `````` ``````# Definition for a binary tree node. # class TreeNode: # def __init__(self, val=0, left=None, right=None): # self.val = val # self.left = left # self.right = right class Solution: def invertTree(self, root: Optional[TreeNode]) -> Optional[TreeNode]: if not root: return root root.left, root.right = root.right, root.left self.invertTree(root.left) self.invertTree(root.right) return root``````