Detect palindrome in linked list
Last updated: November 5, 2025
Quick Overview
Given a singly linked list, write a function to determine if the linked list is a palindrome. A linked list is considered a palindrome if the sequence of values from the head to the tail is the same as the sequence from the tail to the head. The function should return a boolean value: true if the linked list is a palindrome, and false otherwise.
Datadog
November 5, 2025152
14
3,539 solved
Given a singly linked list, write a function to determine if the linked list is a palindrome. A linked list is considered a palindrome if the sequence of values from the head to the tail is the same as the sequence from the tail to the head. The function should return a boolean value: true if the linked list is a palindrome, and false otherwise.
This coding problem is frequently asked during Take-home Project at Datadog. The interviewer is testing your ability to translate a problem into clean, working code while discussing time and space complexity. Datadog 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 you modify your solution to handle streaming input?
- Can you solve this in a single pass?
- Can you optimize the space complexity of your solution?
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 is a palindrome, we can utilize the two-pointer technique. This approach allows us to traverse the linked list in a single pass while also using a stack to keep tr...
Approach
- Initialize two pointers:
slowandfast. Both start at the head of the linked list.slowmoves one step at a time, whilefastmoves two steps. This helps us find the midpoint of the linked l...
Submit Your Answer
