Count maximum path in linked list
Last updated: October 28, 2025
Quick Overview
Given a singly linked list, write a function to count the maximum path length that can be formed by traversing the linked list, where a path is defined as a sequence of nodes starting from any node and ending at any node without revisiting any node. The function should return an integer representing the maximum path length found.
Airbnb
October 28, 202519
3
63 solved
Given a singly linked list, write a function to count the maximum path length that can be formed by traversing the linked list, where a path is defined as a sequence of nodes starting from any node and ending at any node without revisiting any node. The function should return an integer representing the maximum path length found.
Airbnb 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
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
- What happens if the input contains duplicates?
- Can you optimize the space complexity of your solution?
- How would your solution change if the input was sorted?
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Practice DSA ProblemsSample Answer
Problem Analysis
To solve the problem of counting the maximum path length in a singly linked list, we can recognize that this is essentially about finding the longest path in a graph representation where nodes corresp...
Approach
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Initialization: Start by defining a recursive function that will explore each node. Use a set to keep track of visited nodes to prevent cycles.
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DFS Traversal: For each node, mark it as...
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