compression on Binary Tree
Last updated: July 1, 2025
Quick Overview
Given a binary tree, implement a function to compress it by removing all nodes that do not contribute to the path from the root to any leaf node. The function should return a new binary tree that represents the compressed structure. The input will be the root node of the original binary tree, and the output should be the root node of the compressed binary tree.
Anduril
July 1, 20259
5
4,706 solved
Given a binary tree, implement a function to compress it by removing all nodes that do not contribute to the path from the root to any leaf node. The function should return a new binary tree that represents the compressed structure. The input will be the root node of the original binary tree, and the output should be the root node of the compressed binary tree.
This coding problem is frequently asked during Phone Screen at Anduril. The interviewer is testing your ability to translate a problem into clean, working code while discussing time and space complexity. Anduril 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 your solution change if the input was sorted?
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Practice DSA ProblemsSample Answer
Problem Analysis
The problem requires compressing a binary tree by removing nodes that do not form part of any path from the root to a leaf node. This suggests a depth-first search (DFS) approach, as we need to traver...
Approach
We will use a recursive DFS approach to traverse the tree. The steps are as follows:
- Define a recursive function that takes a node as input.
- If the current node is null, return null.
- Recursiv...
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