traversal on Binary Tree
Last updated: September 2, 2025
Quick Overview
Given a binary tree, implement a function to traverse the tree in pre-order, in-order, or post-order and return the values of the nodes in a list. The function should take the root node of the binary tree as input and output a list of node values in the specified traversal order.
Cruise
September 2, 202537
13
3,917 solved
Given a binary tree, implement a function to traverse the tree in pre-order, in-order, or post-order and return the values of the nodes in a list. The function should take the root node of the binary tree as input and output a list of node values in the specified traversal order.
This coding problem is frequently asked during Phone Screen at Cruise. The interviewer is testing your ability to translate a problem into clean, working code while discussing time and space complexity. Cruise expects candidates to write production-quality code, not just solve the puzzle.
What the Interviewer Expects
- Quickly identify the optimal approach and its theoretical basis
- Handle complex algorithm design with multiple interacting components
- Write concise, elegant code under time pressure
- Prove correctness of your approach and discuss alternative solutions
- Optimize beyond the obvious: discuss constant factor improvements
- Address follow-up variations and explain how the solution generalizes
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 parallelize this solution?
- What if the input doesn't fit in memory?
- Can you solve this iteratively instead of recursively (or vice versa)?
- How would your solution change if the input was sorted?
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
The problem requires us to traverse a binary tree in one of three orders: pre-order, in-order, or post-order. The traversal can be efficiently approached using depth-first search (DFS), as it allows u...
Approach
To implement the traversal, we will use a recursive approach for simplicity and clarity:
- Define a recursive function that takes the current node and the result list as parameters.
- Depending on t...
Submit Your Answer
