0226 Invert Binary Tree

# 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 = rightclass Solution:    def invertTree(self, root: Optional[TreeNode]) -> Optional[TreeNode]:        if not root:            return        root.left, root.right = root.right, root.left        if root.left:            self.invertTree(root.left)        if root.right:            self.invertTree(root.right)        return root