BFS on linked list
Last updated: January 20, 2026
Quick Overview
Apply the BFS algorithm on a linked list to solve this optimization problem.
TikTok
Coding & Algorithms
Machine Learning Engineer
TikTok
January 20, 2026Machine Learning Engineer
Phone Screen
Coding & Algorithms
Medium
23
16
4,485 solved
Apply the BFS algorithm on a linked list to solve this optimization problem.
TikTok uses this problem in the Phone Screen 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
Sorting and searching
Hash maps and frequency counting
Dynamic programming and memoization
Graph algorithms and traversal
Binary search and divide and conquer
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?
- What is the worst-case input for your solution?
- Can you solve this in a single pass?
- How would your solution change if the input was sorted?
Sharpen Your Skills on Codemia
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Practice DSA ProblemsSample Answer
Problem Analysis
The problem requires us to apply the BFS (Breadth-First Search) algorithm on a linked list. BFS is particularly suitable here because it explores all the neighbors at the present depth before moving o...
Approach
- Initialization: Start with a queue to manage the BFS traversal and a set to keep track of visited nodes to avoid cycles.
- Enqueue the Head: Add the head of the linked list to the queue. ...
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