traversal on Binary Tree
Last updated: February 11, 2026
Quick Overview
Given a binary tree, implement a function to perform a traversal (in-order, pre-order, or post-order) and return the values of the nodes in an array. Your function should take the root of the binary tree as input and output an array of integers representing the order of traversal.
Lyft
February 11, 2026135
11
106 solved
Given a binary tree, implement a function to perform a traversal (in-order, pre-order, or post-order) and return the values of the nodes in an array. Your function should take the root of the binary tree as input and output an array of integers representing the order of traversal.
Lyft uses this problem in the Take-home Project 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
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 modify your solution to handle streaming input?
- How would your solution change if the input was sorted?
- What is the worst-case input for your solution?
- How would you parallelize this solution?
Sharpen Your Skills on Codemia
Practice similar problems with our interactive workspace, get AI feedback, and track your progress.
Practice DSA ProblemsSample Answer
Problem Analysis
This problem can be solved using Depth-First Search (DFS) traversal methods, specifically in-order, pre-order, or post-order traversal of a binary tree. DFS is suitable here because we need to explore...
Approach
We will implement a recursive approach for the traversal. Let's consider each type of traversal:
- In-order Traversal: For a tree with nodes having values [1, 2, 3]:
- Starting at root (1), g...
Submit Your Answer
