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SymmetricTree.py
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SymmetricTree.py
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# 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 not root:
return True
return self.checkNodes(root.left, root.right)
def checkNodes(self, node1, node2):
if not node1 and not node2:
return True
elif not node1 or not node2:
return False
return node1.val == node2.val and self.checkNodes(node1.left, node2.right) and self.checkNodes(node1.right, node2.left)
########
# Test #
########
# 1
# / \
# 2 2
# / \ / \
# 3 4 4 3
root = TreeNode(1)
node1 = TreeNode(2)
node2 = TreeNode(2)
node3 = TreeNode(3)
node4 = TreeNode(4)
node5 = TreeNode(4)
node6 = TreeNode(3)
root.left = node1
root.right = node2
node1.left = node3
node1.right = node4
node2.left = node5
node2.right = node6
result = Solution().isSymmetric(root)
print(result)
# expected: True
# 1
# / \
# 2 2
# \ \
# 3 3
# root = TreeNode(1)
# node1 = TreeNode(2)
# node2 = TreeNode(2)
# node3 = TreeNode(3)
# node4 = TreeNode(3)
# root.left = node1
# root.right = node2
# node1.right = node3
# node2.right = node4
# expected: False