Detect permutation in linked list
Last updated: January 10, 2026
Quick Overview
Given two linked lists, determine if one linked list is a permutation of the other. You should implement a function that takes the heads of both linked lists as input and returns a boolean value indicating whether the two lists contain the same elements in any order. The solution should consider the frequency of each element and handle cases where the lists may have different lengths.
Visa
January 10, 202695
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1,709 solved
Given two linked lists, determine if one linked list is a permutation of the other. You should implement a function that takes the heads of both linked lists as input and returns a boolean value indicating whether the two lists contain the same elements in any order. The solution should consider the frequency of each element and handle cases where the lists may have different lengths.
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
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
- 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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Problem Analysis
To determine if one linked list is a permutation of another, we need to check if both lists contain the exact same elements with the same frequency. This problem can be effectively solved using a hash...
Approach
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Check Lengths: First, we need to check if the two linked lists have the same length. If not, return
False.- Example: List A has 3 nodes and List B has 4 nodes; return
False.
- Example: List A has 3 nodes and List B has 4 nodes; return
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**Count...
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