Detect palindrome in linked list
Last updated: March 1, 2026
Quick Overview
Given a singly linked list, write a function to determine if the elements of the list form a palindrome. The function should return true if the linked list is a palindrome and false otherwise. The input will be the head node of the linked list, and the output will be a boolean value.
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Given a singly linked list, write a function to determine if the elements of the list form a palindrome. The function should return true if the linked list is a palindrome and false otherwise. The input will be the head node of the linked list, and the output will be a boolean value.
This coding problem is frequently asked during Phone Screen at LinkedIn. The interviewer is testing your ability to translate a problem into clean, working code while discussing time and space complexity. LinkedIn 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
- What is the worst-case input for your solution?
- How would you parallelize this solution?
- Can you optimize the space complexity of your solution?
- What if the input doesn't fit in memory?
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Problem Analysis
To determine if a singly linked list is a palindrome, we can utilize the two-pointer technique alongside a fast and slow pointer approach. This method is efficient because it allows us to find the mid...
Approach
- Initialize two pointers,
slowandfast, both starting at the head of the linked list. Theslowpointer will move one step at a time, while thefastpointer will move two steps at a time.
2...
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