Find connected components in linked list
Last updated: August 14, 2025
Quick Overview
Given a linked list, write a function to identify and return the connected components, where a connected component is defined as a subset of nodes that are connected by edges in the list. The input will be a linked list and a set of node values, and the output should be a list of lists, where each inner list contains the values of nodes in each connected component.
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August 14, 20258
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Given a linked list, write a function to identify and return the connected components, where a connected component is defined as a subset of nodes that are connected by edges in the list. The input will be a linked list and a set of node values, and the output should be a list of lists, where each inner list contains the values of nodes in each connected component.
Coding interviews at Postmates 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
- Identify the correct data structure and algorithm for the problem
- Write clean, bug-free code with proper variable naming
- Analyze time and space complexity correctly
- Handle basic edge cases (empty input, single element)
- Communicate your thought process while coding
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 your solution change if the input was sorted?
- Can you solve this iteratively instead of recursively (or vice versa)?
- How would you modify your solution to handle streaming input?
- How would you parallelize this solution?
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Problem Analysis
To solve the problem of finding connected components in a linked list, we can use a graph traversal approach. The linked list naturally represents a graph where each node points to the next node, and ...
Approach
- Create a set from the input list of node values for O(1) lookups.
- Initialize an empty list to hold the result of connected components.
- Loop through the linked list, and for each node, if ...
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