BFS on linked list
Last updated: September 25, 2025
Quick Overview
Implement a breadth-first search (BFS) algorithm to traverse a linked list. Given the head of a linked list, return an array containing the values of the nodes in the order they are visited using BFS. Ensure your solution handles edge cases, such as an empty list.
Zillow
September 25, 202541
7
3,635 solved
Implement a breadth-first search (BFS) algorithm to traverse a linked list. Given the head of a linked list, return an array containing the values of the nodes in the order they are visited using BFS. Ensure your solution handles edge cases, such as an empty list.
This coding problem is frequently asked during Phone Screen at Zillow. The interviewer is testing your ability to translate a problem into clean, working code while discussing time and space complexity. Zillow 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
- How would you parallelize this solution?
- What if the input doesn't fit in memory?
- Can you solve this in a single pass?
- Can you solve this iteratively instead of recursively (or vice versa)?
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 implement a breadth-first search (BFS) on a linked list. Unlike typical BFS applications on tree or graph structures, here we need to traverse the linked list as a linear st...
Approach
- Initialization: Start by checking if the head of the linked list is null (which indicates an empty list). If it is, return an empty array.
- Traversal: Initialize an empty list to store th...
Submit Your Answer
