Serialization is the process of converting a data structure into a sequence of bits so that it can be stored or transmitted and reconstructed later.
Design an algorithm to serialize and deserialize a binary tree. There is no restriction on how your serialization/deserialization algorithm should work. Just make sure that a binary tree can be serialized to a string and this string can be deserialized to the original tree structure.
**Example 1:**
```
Input: root = [1,2,3,null,null,4,5]
Output: [1,2,3,null,null,4,5]
```
**Example 2:**
```
Input: root = []
Output: []
```
**Clarification:** The input/output format is the same as how LeetCode serializes a binary tree. You do not necessarily need to follow this format.