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# Runtime: 50 ms (Top 60.40%) | Memory: 13.9 MB (Top 94.25%)
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class Solution:
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    def isSymmetric(self, root: Optional[TreeNode]) -> bool:
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        return root is None or self.findSymmetric(root.left, root.right)
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    def findSymmetric(self, left, right):
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        if left is None or right is None:
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            return left == right
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        if left.val != right.val:
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            return False
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        return self.findSymmetric(left.left, right.right) and self.findSymmetric(
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            left.right, right.left
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        )