compression on Binary Tree
Last updated: February 12, 2026
Quick Overview
Given a binary tree, compress it by removing all nodes that do not contribute to the sum of a specified target value. The function should return a new binary tree that retains only the nodes that are part of any path from the root to a leaf that sums up to the target value.
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February 12, 202628
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Given a binary tree, compress it by removing all nodes that do not contribute to the sum of a specified target value. The function should return a new binary tree that retains only the nodes that are part of any path from the root to a leaf that sums up to the target value.
This coding problem is frequently asked during Technical Screen at Zoom. The interviewer is testing your ability to translate a problem into clean, working code while discussing time and space complexity. Zoom 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?
- How would you modify your solution to handle streaming input?
- How would you test this solution thoroughly?
- What if the input doesn't fit in memory?
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Practice DSA ProblemsSample Answer
Problem Analysis
To solve the problem of compressing a binary tree based on a target sum, we can recognize that this is essentially a tree traversal problem where we need to identify paths that yield the target sum. T...
Approach
- Depth-First Search (DFS): We will implement a recursive function that traverses the tree from the root to the leaves.
- Path Sum Calculation: As we traverse, we will maintain a running su...
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