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；

 1 # Definition for a  binary tree node
 2 # class TreeNode:
 3 #     def __init__(self, x):
 4 #         self.val = x
 5 #         self.left = None
 6 #         self.right = None
 7 
 8 class Solution:
 9     # @param root, a tree node
10     # @return a boolean
11     def isSymmetric(self,root):
12         ret = True
13         q = []
14         s = []
15         if root != None:#注意root为空
16             q.append(root)
17             s.append(root.val)
18         while (len(q) != 0 and ret == True):
19             h = 0
20             t = len(s) - 1
21             while (h < t):
22                 if (s[h] != s[t]):
23                     ret = False
24                     break
25                 h+=1#这里忘记控制h和t了
26                 t-=1
27             tq = q
28             s = []
29             q = []
30             while (len(tq) != 0 and ret == True):
31                 t = tq.pop(0)#pop默认弹出最后一个值
32                 if t.left != None:
33                     q.append(t.left)
34                     s.append(t.left.val)
35                 else:
36                     s.append(9999)
37                 if t.right != None:
38                     q.append(t.right)
39                     s.append(t.right.val)
40                 else:
41                     s.append(9999)
42         return ret