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0101_symmetricTree.py
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0101_symmetricTree.py
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# 0101 - Symmetric Tree
'''
Question:
Given the root of a binary tree, check whether it is a mirror of itself (i.e., symmetric around its center).
'''
# Definition for a binary tree node.
class TreeNode(object):
def __init__(self, val=0, left=None, right=None):
self.val = val
self.left = left
self.right = right
class Solution(object):
def isSymmetric(self, root):
"""
:type root: TreeNode
:rtype: bool
"""
if not root:
return True
return self.checkSymmetric(root.left, root.right)
def checkSymmetric(self, subTree_1, subTree_2):
if subTree_1 == None and subTree_2 == None:
return True
if subTree_1 == None or subTree_2 == None:
return False
return (subTree_1.val == subTree_2.val) and self.checkSymmetric(subTree_1.left, subTree_2.right) and self.checkSymmetric(subTree_1.right,subTree_2.left)
if __name__ == '__main__':
root = [1,2,2,3,4,4,3]
root = [1,2,2,None,3,None,3]
tree = TreeNode(val = root[0],
left = TreeNode(val = root[1], left = TreeNode(val = root[3]), right = TreeNode(val = root[4])),
right = TreeNode(val = root[2], left = TreeNode(val = root[5]), right = TreeNode(val = root[6])))
sol = Solution()
print(sol.isSymmetric(tree))