partitioning on Binary Tree
Last updated: April 10, 2026
Quick Overview
Perform a compression on a binary tree and return the result.
Grubhub
Coding & Algorithms
Software Engineer
Grubhub
April 10, 2026Software Engineer
Onsite
Coding & Algorithms
Medium
10
8
3,191 solved
Perform a compression on a binary tree and return the result.
Grubhub uses this problem in the Onsite to evaluate your algorithmic thinking. They expect you to discuss multiple approaches, analyze trade-offs between them, and implement the optimal solution with clean, readable code.
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
Time and space complexity analysis
Common algorithm patterns (sliding window, two pointers, BFS/DFS)
Hash maps and frequency counting
Edge cases and input validation
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 test this solution thoroughly?
- How would you modify your solution to handle streaming input?
- How would your solution change if the input was sorted?
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Practice DSA ProblemsSample Answer
Problem Analysis
The problem requires us to partition a binary tree in such a way that we can represent it in a compressed format. The key pattern here is Depth First Search (DFS), which is suitable for tree traversal...
Approach
- Define a recursive DFS function that will take a node of the tree as an argument.
- Base Case: If the node is null, return an empty string.
- Recursive Case: For each node, retrieve t...
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