The traversal logic itself wasn't the hard part.
First, clarify the exact traversal order and output format with the interviewer, as the question allows multiple options. Then, choose the appropriate data structure (e.g., queue for level-order, map for vertical order) and implement the traversal, ensuring the output matches the specified format precisely. Finally, walk through a small example to verify correctness and discuss time/space complexity.
Pro tip: Snapchat values clean, production-ready code, so write modular functions with clear variable names and handle edge cases like empty trees or single nodes. Also, mention how you would test the solution with unit tests, showing you think beyond just solving the problem.
Ask the interviewer to confirm the traversal type (level-order, vertical, or boundary) and the exact output format (e.g., one line per level, comma-separated, serialized string). Clarify any constraints like tree size or node values.
Select the appropriate data structure: queue for level-order, map (e.g., TreeMap) for vertical order, or recursive/iterative with boundary flags for boundary traversal. Outline the algorithm steps, including how to handle the output format.
Write clean, modular code with helper functions if needed. Ensure the traversal logic correctly processes nodes in the required order and builds the output string or list according to the format.
Walk through a small example tree to verify the output format. Test edge cases: empty tree, single node, skewed tree, and full tree. Check for off-by-one errors and correct handling of null children.
State the time and space complexity (usually O(n) time, O(n) space for queue/map). Discuss potential optimizations or trade-offs, such as using iterative vs recursive approaches or handling large trees.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.