Transform linked list to adjacency list
Last updated: August 6, 2025
Quick Overview
Given a singly linked list where each node contains a value and a reference to a list of its neighbors, transform this linked list into an adjacency list representation. The output should be a dictionary where each key is a node's value and the corresponding value is a list of its neighbors' values. Ensure that the adjacency list accurately reflects the connections represented in the linked list.
Cloudflare
August 6, 20255
6
570 solved
Given a singly linked list where each node contains a value and a reference to a list of its neighbors, transform this linked list into an adjacency list representation. The output should be a dictionary where each key is a node's value and the corresponding value is a list of its neighbors' values. Ensure that the adjacency list accurately reflects the connections represented in the linked list.
Cloudflare 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
- How would you modify your solution to handle streaming input?
- How would you parallelize this solution?
- How would you test this solution thoroughly?
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Problem Analysis
The problem requires transforming a singly linked list into an adjacency list representation. Each node in the linked list contains a value and references to its neighbors, which can be considered as ...
Approach
- Initialize an empty dictionary
adjacency_listto store the adjacency list representation. - Create a variable
currentto traverse the linked list starting from the head. - While
currentis ...
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