Invert Tree

LeetCode Problem

# https://leetcode.com/problems/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 = right


class Solution:
    def invertTree(self, root):
        if root:
            self.invertTree(root.left)
            self.invertTree(root.right)
            root.left, root.right = root.right, root.left
        return root