1+ # Definition for a binary tree node.
2+ # class TreeNode:
3+ # def __init__(self, val=0, left=None, right=None):
4+ # self.val = val
5+ # self.left = left
6+ # self.right = right
7+ class Solution :
8+ def isSymmetric (self , root : Optional [TreeNode ]) -> bool :
9+ def isMirror (root1 , root2 ):
10+ # If both trees are empty, then they are mirror images
11+ if root1 is None and root2 is None :
12+ return True
13+ 14+ """ For two trees to be mirror images,
15+ the following three conditions must be true
16+ 1 - Their root node's key must be same
17+ 2 - left subtree of left tree and right subtree
18+ of the right tree have to be mirror images
19+ 3 - right subtree of left tree and left subtree
20+ of right tree have to be mirror images
21+ """
22+ if (root1 is not None and root2 is not None ):
23+ if root1 .val == root2 .val :
24+ return (isMirror (root1 .left , root2 .right ) and
25+ isMirror (root1 .right , root2 .left ))
26+ # If none of the above conditions is true then root1
27+ # and root2 are not mirror images
28+ return False
29+ 30+ return isMirror (root , root )
31+
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