剑指offer 序列化二叉树

# -*- coding:utf-8 -*-
# class TreeNode:
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None
class Solution:
    def Serialize(self, root):
        valuelist = []
        self.preorder(root, valuelist)
        # 将结点值序列转化为一个字符串
        return ','.join(map(str, valuelist))

    def preorder(self, root, valuelist):
        if not root:
            # 对于空结点，返回#字符加以标识
            valuelist.append('#')
            return None
        valuelist.append(root.val)
        self.preorder(root.left, valuelist)
        self.preorder(root.right, valuelist)

    # write code here
    def Deserialize(self, s):
        valuelist = s.split(',')
        root = self.preorderdes(valuelist)
        return root

    def preorderdes(self, valuelist):
        if len(valuelist) == 0 or valuelist[0] == '':
            return None
        # 遇到#字符，直接删除，返回空结点
        if valuelist[0] == '#':
            del valuelist[0]
            return None
        root = TreeNode(int(valuelist[0]))
        del valuelist[0]
        root.left = self.preorderdes(valuelist)
        root.right = self.preorderdes(valuelist)
        return root