Two Pointers on linked list
Last updated: October 23, 2025
Quick Overview
Given a linked list, implement the Two Pointers technique to determine if there is a cycle in the list. Your function should return a boolean value: true if a cycle exists, and false otherwise.
Palantir
October 23, 20256
3
2,617 solved
Given a linked list, implement the Two Pointers technique to determine if there is a cycle in the list. Your function should return a boolean value: true if a cycle exists, and false otherwise.
Palantir uses this problem in the Technical Screen 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
- 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
- How would you modify your solution to handle streaming input?
- What is the worst-case input for your solution?
- What happens if the input contains duplicates?
- 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
In this problem, we are tasked with detecting a cycle in a linked list using the Two Pointers technique. This method is particularly suitable because it allows us to traverse the linked list with two ...
Approach
- Initialize two pointers,
slowandfast. Set both to the head of the linked list. - Move
slowby one step andfastby two steps in each iteration. - Check if
fastorfast.nextis `Non...
Submit Your Answer
