Question

Serialization is the process of converting a data structure or object into a sequence of bits so that it can be stored in a file or memory buffer, or transmitted across a network connection link to be reconstructed later in the same or another computer environment. Design an algorithm to serialize and deserialize a binary tree. There is no restriction on how your serialization/deserialization algorithm should work. You just need to ensure that a binary tree can be serialized to a string and this string can be deserialized to the original tree structure.

For example, you may serialize the following tree
1
/ \
2 3
/ \
4 5
as "[1,2,3,null,null,4,5]", just the same as how LeetCode OJ serializes a binary tree. You do not necessarily need to follow this format, so please be creative and come up with different approaches yourself.Note: Do not use class member/global/static variables to store states. Your serialize and deserialize algorithms should be stateless.

Answer 1

For serialization, perform a depth-first traversal of the binary tree, appending each node's value to the result string. Represent null nodes as a designated character (e.g., 'null'). For deserialization, split the serialized string to obtain node values. Recreate the binary tree using a recursive function that builds nodes based on the obtained values.

Step-by-step explanation:

To serialize a binary tree, a depth-first traversal is employed. Starting from the root, each node's value is appended to the result string. Null nodes are represented by a designated character, such as 'null'. This recursive process ensures that the entire tree is represented in the serialized string. For example, in the given tree, the serialization might be "[1,2,3,null,null,4,5]".

Deserialization involves splitting the serialized string to obtain the values. Using these values, a recursive function reconstructs the binary tree. It starts with the root, assigns values, and then recursively constructs the left and right subtrees. This approach ensures that the original tree structure is faithfully recreated from the serialized string.

The algorithm is stateless, avoiding the use of class member/global/static variables to store states. Instead, it relies on the input data and local variables during the serialization and deserialization processes. This stateless design enhances the algorithm's versatility and makes it suitable for different programming environments and use cases.