二叉树的序列化与反序列化
Serialize and Deserialize Binary Tree
题目详情
问题：二叉树的序列化与反序列化
考察：树、递归
来源：Citadel
链接：https://www.jointaro.com/interviews/questions/serialize-and-deserialize-binary-tree/
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.
Clarification: The input/output 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.
Example 1:
Input: root = [1,2,3,null,null,4,5] Output: [1,2,3,null,null,4,5]
Example 2:
Input: root = [] Output: []
Constraints:
- The number of nodes in the tree is in the range
[0, 104]. -1000 <= Node.val <= 1000
解析
思路：用前序遍历序列化节点值，并用特殊标记表示空节点。反序列化时按同样前序顺序递归读取，遇到空标记返回 null。
复杂度：序列化和反序列化都是 O(n)，空间 O(n)。