Serialization is the process of converting a data structure or object into a sequence of bits so that it can be stored in a file or memory buffer, or transmitted across a network connection link to be reconstructed later in the same or another computer environment.
Design an algorithm to serialize and deserialize a binary tree. There is no restriction on how your serialization/deserialization algorithm should work. You just need to ensure that a binary tree can be serialized to a string and this string can be deserialized to the original tree structure.
Example:
You may serialize the following tree:
1
/ 2 3
/ 4 5
as "[1,2,3,null,null,4,5]"
Clarification: The above format is the same as how LeetCode serializes a binary tree. You do not necessarily need to follow this format, so please be creative and come up with different approaches yourself.
Note: Do not use class member/global/static variables to store states. Your serialize and deserialize algorithms should be stateless.
序列化和反序列化二叉树。解法主要是两种层序遍历和前序遍历。
前序遍历基本采用递归写法，需要保存一个全局变量来告诉代码，现在在处理数组的第几个数字。比较麻烦。
所以这里给出层序遍历的代码：
class Codec: def serialize(self, root): """Encodes a tree to a single string. :type root: TreeNode :rtype: str """ if root is None: return "" res = [] queue = collections.deque() queue.append(root) while queue: node = queue.popleft() if node: res.append(str(node.val)) queue.append(node.left) queue.append(node.right) else: res.append(‘#‘) return ",".join(res) def deserialize(self, data): """Decodes your encoded data to tree. :type data: str :rtype: TreeNode """ if data == "": return None res = data.split(‘,‘) queue = collections.deque() root = TreeNode(res[0]) i = 1 queue.append(root) while queue: cur = queue.popleft() leftval = res[i] if leftval != ‘#‘: left = TreeNode(int(leftval)) cur.left = left queue.append(left) i += 1 rightval = res[i] if rightval != ‘#‘: right = TreeNode(int(rightval)) cur.right = right queue.append(right) i += 1 return root
注意这里的写法对于[1,2,3,null,null,4,5]的序列化结果为“1,2,3,#,#,4,5，#，#，#，#”
同时注意这里的反序列化实际利用第一层只有根节点的信息，所以先放到queue中。
Serialize and Deserialize Binary Tree
原文：https://www.cnblogs.com/sherylwang/p/9735858.html