Leetcode【101】Symmetric Tree （Python版）

python函数中定义函数，只能这么写

# Definition for a binary tree node.
# class TreeNode(object):
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = Noneclass Solution(object):def isSymmetric(self, root):""":type root: TreeNode:rtype: bool"""def helper(t1,t2):if not t1 and not t2:return Trueif not t1 or not t2:return Falsereturn (t1.val == t2.val) and helper(t1.left,t2.right) and helper(t1.right,t2.left)return helper(root,root)