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