請實現一個函數,用來判斷一棵二叉樹是不是對稱的。如果一個二叉樹同此二叉樹的鏡像是同樣的,定義其爲對稱的。
#-*- coding:utf-8 -*-
class TreeNode:
def __init__(self,x):
self.val=x
self.left=None
self.right=None
class Solution:
def isSymmetrical(self,pRoot):
def isMirror(left, right):
if left==None and right==None:
return True
elif left==None or right==None:
return False
if left.val!=right.val:
ret1=isMirror(left.left, right.right)
ret2=isMirror(left.right, right.left)
return ret1 and ret2
if pRoot == None:
return True
return isMirror(pRoot.left, pRoot.right)