Detect permutation in matrix
Last updated: October 24, 2025
Quick Overview
Given a matrix, determine if any of its rows or columns contain a permutation of a given target array. The function should return true if at least one permutation is found, and false otherwise. The input consists of a 2D array (matrix) and a 1D array (target), and the output is a boolean value.
ServiceNow
October 24, 2025278
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Given a matrix, determine if any of its rows or columns contain a permutation of a given target array. The function should return true if at least one permutation is found, and false otherwise. The input consists of a 2D array (matrix) and a 1D array (target), and the output is a boolean value.
This coding problem is frequently asked during Onsite at ServiceNow. The interviewer is testing your ability to translate a problem into clean, working code while discussing time and space complexity. ServiceNow 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
- Can you optimize the space complexity of your solution?
- What happens if the input contains duplicates?
- Can you solve this in a single pass?
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Practice DSA ProblemsSample Answer
Problem Analysis
To determine if any row or column in the matrix contains a permutation of the target array, we can identify this as a problem that requires frequency counting. The underlying pattern is that if two se...
Approach
- Count frequencies of the target array: First, create a frequency dictionary for the target array. For example, if the target array is
[1, 2, 2], the frequency map would be{1: 1, 2: 2}. - ...
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