Serialize and Deserialize Binary Tree

Design an algorithm to serialize a binary tree into a string, and deserialize that string back into the original tree.

Serialization is the process of converting a data structure into a sequence of characters so that it can be stored or transmitted and reconstructed later.

You need to implement a Codec class (or equivalent) with two methods:

• serialize(root) — Encodes a tree to a single string.
• deserialize(data) — Decodes the string back to a tree.

Your serialization/deserialization algorithm should work correctly — the tree reconstructed from deserialize(serialize(root)) must be structurally identical to the original tree with the same node values.

There is no restriction on how your serialization format works. Any valid format is accepted as long as the round-trip produces the correct tree.

The tree is given as a level-order array where null represents a missing node. For example, [1,2,3,null,null,4,5] represents:

      1
     / \
    2   3
       / \
      4   5