serialization on Binary Tree
Last updated: December 28, 2025
Quick Overview
Implement a function to serialize a binary tree into a string representation and a function to deserialize the string back into the original binary tree structure. The input will be the root node of the binary tree, and the output should be a string for serialization and the root node for deserialization. Ensure that your solution handles edge cases, such as empty trees.
Plaid
December 28, 202561
13
3,250 solved
Implement a function to serialize a binary tree into a string representation and a function to deserialize the string back into the original binary tree structure. The input will be the root node of the binary tree, and the output should be a string for serialization and the root node for deserialization. Ensure that your solution handles edge cases, such as empty trees.
This coding problem is frequently asked during Technical Screen at Plaid. The interviewer is testing your ability to translate a problem into clean, working code while discussing time and space complexity. Plaid expects candidates to write production-quality code, not just solve the puzzle.
What the Interviewer Expects
- Recognize the underlying problem pattern (sliding window, two pointers, BFS/DFS, etc.)
- Discuss multiple approaches and trade-offs before coding
- Implement an optimal solution with clean, production-quality code
- Handle all edge cases including boundary conditions and invalid input
- Optimize both time and space complexity with clear justification
- Test your solution systematically with well-chosen examples
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
- Can you solve this in a single pass?
- What happens if the input contains duplicates?
- What if the input doesn't fit in memory?
- How would you test this solution thoroughly?
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Practice DSA ProblemsSample Answer
Problem Analysis
The problem involves serializing and deserializing a binary tree. The best approach to solve this is to use a Depth-First Search (DFS) traversal pattern. This is appropriate here because we want t...
Approach
- Serialization:
- Create a recursive function that takes a node as input.
- If the node is null, append 'None' to the result string.
- Otherwise, append the node's value, and recursivel...
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