Transform linked list to adjacency list
Last updated: October 9, 2025
Quick Overview
Given a singly linked list where each node contains a value and a reference to the next node, transform this linked list into an adjacency list representation of a graph. Each node's value will serve as a vertex, and the adjacency list should reflect the connections based on the linked list structure, where each vertex points to a list of its adjacent vertices. The output should be a dictionary where keys are the node values and values are lists of connected node values.
Palantir
October 9, 2025293
11
2,898 solved
Given a singly linked list where each node contains a value and a reference to the next node, transform this linked list into an adjacency list representation of a graph. Each node's value will serve as a vertex, and the adjacency list should reflect the connections based on the linked list structure, where each vertex points to a list of its adjacent vertices. The output should be a dictionary where keys are the node values and values are lists of connected node values.
Coding interviews at Palantir focus on problem-solving approach as much as the final solution. The interviewer wants to see you break down the problem, consider edge cases, and optimize iteratively. Communication throughout the process is key.
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 test this solution thoroughly?
- What is the worst-case input for your solution?
- How would you parallelize this solution?
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Problem Analysis
In this problem, we are required to transform a singly linked list into an adjacency list representation of a graph. The specific pattern that applies here is a traversal mechanism, as we need to iter...
Approach
- Initialize a dictionary
adjacency_listto hold the vertex connections. - Set up a pointer
currentthat starts at the head of the linked list. - Iterate through the linked list: Wh...
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