Spent too long second-guessing the serialization format.
Clarify the encoding format (e.g., string or array) and constraints, then design a serialization that captures both node values and the number of children. Use a delimiter-based approach with preorder traversal, and ensure the decoder can reconstruct the tree by parsing the encoded data.
Pro tip: Discuss trade-offs between different encoding schemes (e.g., delimiter-based vs. length-prefixed) and mention edge cases like empty trees, nodes with many children, and values containing delimiters. This shows depth and foresight.
Ask about the expected encoding format (string, array, etc.), allowed characters, and whether the tree can be empty or have nodes with special values. Confirm if the encoding needs to be human-readable or space-efficient.
Decide on a serialization method, such as preorder traversal with delimiters and child counts, or length-prefixed values. Explain why this approach handles N-ary trees and avoids ambiguity.
Write a recursive or iterative function that traverses the tree and appends node values and child counts (or delimiters) to the encoded output. Ensure proper handling of null nodes and escaping if needed.
Parse the encoded data to reconstruct the tree. Use a queue or recursion to read node values and child counts, creating nodes and attaching children accordingly. Validate the input to handle malformed data.
Walk through examples like a single node, a deep tree, and a wide tree. Discuss time and space complexity, and potential improvements or alternative approaches.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.