Detect permutation in array
Last updated: August 16, 2025
Quick Overview
Given two strings, determine if one string is a permutation of the other. You should implement a function that takes two input strings and returns a boolean indicating whether the second string can be formed by rearranging the characters of the first string. The solution should handle cases with different character counts and ignore spaces and case sensitivity.
OpenAI
August 16, 202593
11
3,789 solved
Given two strings, determine if one string is a permutation of the other. You should implement a function that takes two input strings and returns a boolean indicating whether the second string can be formed by rearranging the characters of the first string. The solution should handle cases with different character counts and ignore spaces and case sensitivity.
Coding interviews at OpenAI 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
- Can you optimize the space complexity of your solution?
- Can you solve this iteratively instead of recursively (or vice versa)?
- How would you modify your solution to handle streaming input?
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Practice DSA ProblemsSample Answer
Problem Analysis
To determine if one string is a permutation of another, we can utilize the property that both strings must contain the same characters with the same frequencies. This problem can be effectively solved...
Approach
- Normalize the Input: Convert both strings to lowercase and remove any spaces. For example, for the strings 'Listen' and 'Silent', we convert them to 'listen' and 'silent'.
- **Count Frequencie...
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