208. 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 structure. Serialization converts the tree into a format that can be stored or transmitted, and deserialization reconstructs the tree from that format. There is no restriction on how your serialization and deserialization algorithms should work, as long as a tree can be serialized and then deserialized back to the same structure.