Detect subsequence in linked list
Last updated: January 25, 2026
Quick Overview
Given a linked list and a sequence of integers, determine if the sequence is a subsequence of the linked list. The function should return true if the sequence can be found in the linked list in the same order, but not necessarily consecutively; otherwise, return false.
PlanetScale
January 25, 202620
14
4,146 solved
Given a linked list and a sequence of integers, determine if the sequence is a subsequence of the linked list. The function should return true if the sequence can be found in the linked list in the same order, but not necessarily consecutively; otherwise, return false.
Coding interviews at PlanetScale 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
- What is the worst-case input for your solution?
- Can you solve this in a single pass?
- How would you test this solution thoroughly?
- Can you optimize the space complexity of your solution?
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Problem Analysis
To determine if a sequence of integers is a subsequence of a linked list, we can utilize a two-pointer technique. The reason this approach is effective here is that we can traverse through the linked ...
Approach
- Initialize two pointers:
list_ptrfor traversing the linked list andseq_ptrfor traversing the sequence. - Start both pointers at the beginning of their respective structures.
- Iterate th...
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