Detect permutation in matrix
Last updated: April 17, 2026
Quick Overview
Given a matrix of characters and a target string, determine if any row or column in the matrix contains a permutation of the target string. The function should return true if such a permutation exists, and false otherwise. The input will be a 2D array of characters and a string, and the output should be a boolean value.
Palantir
April 17, 2026122
7
211 solved
Given a matrix of characters and a target string, determine if any row or column in the matrix contains a permutation of the target string. The function should return true if such a permutation exists, and false otherwise. The input will be a 2D array of characters and a string, and the output should be a boolean value.
This coding problem is frequently asked during Technical Screen at Palantir. The interviewer is testing your ability to translate a problem into clean, working code while discussing time and space complexity. Palantir expects candidates to write production-quality code, not just solve the puzzle.
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
- What is the worst-case input for your solution?
- Can you optimize the space complexity of your solution?
- How would you parallelize this solution?
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Practice DSA ProblemsSample Answer
Problem Analysis
We need to determine if any row or column in a given matrix contains a permutation of a target string. This suggests that we should focus on frequency counting because permutations have the same chara...
Approach
- Count the frequency of characters in the target string using a hash map.
- For example, for the target string 'abc', the frequency map would be {'a': 1, 'b': 1, 'c': 1}.
- **Iterate through...
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