Detect permutation in matrix
Last updated: April 25, 2026
Quick Overview
Given a matrix of integers, determine if any row or column is a permutation of another row or column. You should return a boolean value indicating whether such a permutation exists. The input will be a 2D array of integers, and the output will be true if a permutation is found, otherwise false.
HubSpot
April 25, 2026100
7
3,508 solved
Given a matrix of integers, determine if any row or column is a permutation of another row or column. You should return a boolean value indicating whether such a permutation exists. The input will be a 2D array of integers, and the output will be true if a permutation is found, otherwise false.
Coding interviews at HubSpot focus on problem-solving approach as much as the final solution. The interviewer wants to see you break down the problem, consider edge cases, and optimize iteratively. Communication throughout the process is key.
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 if the input doesn't fit in memory?
- How would you modify your solution to handle streaming input?
- Can you solve this iteratively instead of recursively (or vice versa)?
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Practice DSA ProblemsSample Answer
Problem Analysis
To determine if any row or column in a given matrix is a permutation of another, we need to identify the underlying pattern of how permutations work. A permutation of an array contains the same elemen...
Approach
- Extract Rows and Columns: First, we will extract all rows and columns from the matrix into separate lists. For example, given the matrix:
[[1, 2, 3], [3, 2, 1], [4, 5, 6]] ...
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