leetcode:Symmetric Tree【Python版】

#error caused by：
#1:{} 没有考虑None输入
#2:{1,2,2} 没有控制h和t
#3：{4,-57,-57,#,67,67,#,#,-97,-97} 没有考虑负号，将s从str变成list，采用9999代表空数值；

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逐层进行对称性验证，出现不对称就结束；

# Definition for a  binary tree node
# class TreeNode:
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None

class Solution:
# @param root, a tree node
# @return a boolean
def isSymmetric(self,root):
ret = True
q = []
s = []
if root != None:#注意root为空
q.append(root)
s.append(root.val)
while (len(q) != 0 and ret == True):
h = 0
t = len(s) - 1
while (h < t):
if (s[h] != s[t]):
ret = False
break
h+=1#这里忘记控制h和t了
t-=1
tq = q
s = []
q = []
while (len(tq) != 0 and ret == True):
t = tq.pop(0)#pop默认弹出最后一个值
if t.left != None:
q.append(t.left)
s.append(t.left.val)
else:
s.append(9999)
if t.right != None:
q.append(t.right)
s.append(t.right.val)
else:
s.append(9999)
return ret