Serialize and Deserialize Binary Tree

Implement an algorithm to serialize and deserialize a binary tree. Serialization involves converting the tree to a string, and deserialization reconstructs the tree from the string. Assume both input and output are in the form of a binary tree's preorder traversal. Node values are integers. Tree can have up to 10^4 nodes. Requirements: Design serialize and deserialize functions. Include test cases to verify the implementation. Example: Input: # Example binary tree 1 / \ 2 3 / \ 4 5 Output: [1,2,3,null,null,4,5] Example Input [1,2,3,null,null,4,5]