Detect palindrome in linked list
Last updated: January 2, 2026
Quick Overview
Given a singly linked list, implement a function to determine if the linked list represents a palindrome. A linked list is considered a palindrome if the sequence of values reads the same forwards and backwards. The function should return a boolean value indicating whether the linked list is a palindrome.
Cloudflare
January 2, 20260
12
571 solved
Given a singly linked list, implement a function to determine if the linked list represents a palindrome. A linked list is considered a palindrome if the sequence of values reads the same forwards and backwards. The function should return a boolean value indicating whether the linked list is a palindrome.
Cloudflare uses this problem in the Take-home Project 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
- 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 your solution change if the input was sorted?
- How would you parallelize this solution?
- Can you optimize the space complexity of your solution?
- Can you solve this iteratively instead of recursively (or vice versa)?
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Problem Analysis
To determine if a singly linked list is a palindrome, we can leverage the properties of palindromes and the structure of a linked list. The two-pointer technique is ideal here, as it allows us to trav...
Approach
- Find the Midpoint: Use two pointers,
slowandfast. Moveslowone step andfasttwo steps untilfastreaches the end. At this point,slowwill be at the midpoint. - **Reverse the S...
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