Detect palindrome in linked list
Last updated: January 18, 2026
Quick Overview
Given a singly linked list, determine if the sequence of values forms a palindrome. A palindrome reads the same forwards and backwards. The function should return a boolean value indicating whether the linked list is a palindrome.
HashiCorp
January 18, 202613
11
864 solved
Given a singly linked list, determine if the sequence of values forms a palindrome. A palindrome reads the same forwards and backwards. The function should return a boolean value indicating whether the linked list is a palindrome.
This coding problem is frequently asked during Technical Screen at HashiCorp. The interviewer is testing your ability to translate a problem into clean, working code while discussing time and space complexity. HashiCorp expects candidates to write production-quality code, not just solve the puzzle.
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 your solution change if the input was sorted?
- Can you solve this iteratively instead of recursively (or vice versa)?
- What if the input doesn't fit in memory?
- What happens if the input contains duplicates?
Sharpen Your Skills on Codemia
Practice similar problems with our interactive workspace, get AI feedback, and track your progress.
Practice DSA ProblemsSample Answer
Problem Analysis
To determine if a singly linked list forms a palindrome, we can utilize the two-pointer technique. This technique allows us to traverse the list with two pointers at varying speeds to find the mid...
Approach
- Find the midpoint of the linked list: Use two pointers,
slowandfast. Initialize both at the head; moveslowby one step andfastby two steps untilfastreaches the end. By the time...
Submit Your Answer
