Serialize and Deserialize Binary Tree
Last updated: March 3, 2025
Quick Overview
Design an algorithm to encode a binary tree to a string and decode it back. Tests recursion, string manipulation, and tree reconstruction.
ByteDance
March 3, 20258
12
4,569 solved
Design an algorithm to encode a binary tree to a string and decode it back. Tests recursion, string manipulation, and tree reconstruction.
Tree serialization is a ByteDance favorite that combines tree traversal with string processing. Tests both coding ability and design thinking.
What the Interviewer Expects
- Implement both serialize and deserialize functions
- Handle null nodes explicitly in the encoding
- Use preorder traversal for straightforward reconstruction
- Handle edge cases (empty tree, single node, skewed tree)
- Discuss space efficiency of different encodings
Key Topics to Cover
How to Approach This
- Clarify input constraints and edge cases before writing code.
- Walk through your approach verbally and confirm with the interviewer before coding.
- Start with a brute force solution, then optimize. Mention time and space complexity.
- Test your solution with examples, including edge cases like empty input or duplicates.
- Consider common patterns: sliding window, two pointers, hash map, BFS/DFS, dynamic programming.
Possible Follow-up Questions
- How would you serialize an N-ary tree?
- What if you need a compact binary encoding?
- How would you handle trees with very large node values?
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Practice DSA ProblemsSample Answer
Implementation
```python class Codec: def serialize(self, root): tokens = [] def dfs(node): if not node: tokens.appen...
Why Preorder Works
Preorder (root, left, right) with null markers gives enough information to uniquely reconstruct the tree. Each null marker indicates a leaf boundary, ...
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