Detect permutation in linked list

Last updated: January 10, 2026

Quick Overview

Given string, detect all occurrences of the palindrome pattern.

Visa
Coding & Algorithms
Machine Learning Engineer
Visa
January 10, 2026
Machine Learning Engineer
Phone Screen
Coding & Algorithms
Medium

95

11

1,709 solved


Given string, detect all occurrences of the palindrome pattern.

Visa uses this problem in the Phone 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
  • 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
Tree structures and recursion
Edge cases and input validation
Hash maps and frequency counting
Common algorithm patterns (sliding window, two pointers, BFS/DFS)
How to Approach This
  1. Clarify input constraints and edge cases before writing code.
  2. Walk through your approach verbally and confirm with the interviewer before coding.
  3. Start with a brute force solution, then optimize. Mention time and space complexity.
  4. Test your solution with examples, including edge cases like empty input or duplicates.
  5. Consider common patterns: sliding window, two pointers, hash map, BFS/DFS, dynamic programming.
Possible Follow-up Questions
  • Can you optimize the space complexity of your solution?
  • How would your solution change if the input was sorted?
  • What if the input doesn't fit in memory?
  • How would you modify your solution to handle streaming input?
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