Serialize Binary Tree for Messenger | Dataford Interview Questions

In Meta Messenger infrastructure, tree-shaped data may need to be converted into a string for transport and rebuilt later. Implement functions to serialize a binary tree into a string and deserialize that string back into the original tree.

A correct solution must preserve both node values and tree structure, including missing children.

Formal Specification

Input to serialize: the root of a binary tree where each node has fields val, left, and right
Output from serialize: a string representation of the tree
Input to deserialize: a string produced by serialize
Output from deserialize: the reconstructed root node

Use the string format produced by a level-order traversal with # representing null children and values separated by commas.

Constraints

0 <= number of nodes <= 10^4
-1000 <= Node.val <= 1000
Input to deserialize is always a valid string produced by serialize
Tree may be balanced, skewed, or sparse

Function Signature

def serialize_deserialize(root):

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