Serialize and Deserialize Binary Tree

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

Serialization is the process of converting a data structure into a sequence of bits so it can be stored in a file, memory buffer, or transmitted across a network and reconstructed later in the same or another environment.

You do not need to follow any particular format; the only requirement is that deserialize(serialize(root)) produces a tree that is structurally identical to root with the same node values.

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Example 1

    1
   / \
  2   3
     / \
    4   5

Input: root = [1,2,3,null,null,4,5]
Output: [1,2,3,null,null,4,5]
Explanation: The tree is serialized to some string and then deserialized back. The round-trip must produce the exact same tree.

Example 2

Input: root = []
Output: []
Explanation: An empty tree serializes and deserializes back to an empty tree.

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Constraints

• The number of nodes in the tree is in the range [0, 10^4].
• -1000 <= Node.val <= 1000