# Definition for a binary tree node.
# class TreeNode:
# def __init__(self, x):
# self.val = x
# self.left = None
# self.right = None
class Solution:
def isSymmetric(self, root: TreeNode) -> bool:
if root is None:
return True
return self.isSymmetricRecu(root.left, root.right)
def isSymmetricRecu(self, left, right):
if left is None and right is None:
return True
if left is None or right is None or left.val != right.val:
return False
return self.isSymmetricRecu(left.left, right.right) and self.isSymmetricRecu(left.right, right.left)
