Detect subsequence in array
Last updated: May 5, 2026
Quick Overview
Given array, detect all occurrences of the palindrome pattern.
Square/Block
Coding & Algorithms
Software Engineer
Square/Block
May 5, 2026Software Engineer
Take-home Project
Coding & Algorithms
Medium
286
13
1,642 solved
Given array, detect all occurrences of the palindrome pattern.
Coding interviews at Square/Block 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
Binary search and divide and conquer
Graph algorithms and traversal
Common algorithm patterns (sliding window, two pointers, BFS/DFS)
Tree structures and recursion
Data structure selection and trade-offs
Time and space complexity analysis
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 solve this iteratively instead of recursively (or vice versa)?
- How would you modify your solution to handle streaming input?
- How would you test this solution thoroughly?
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Practice DSA ProblemsSample Answer
Problem Analysis
To detect all occurrences of a palindrome pattern in an array, we can utilize the two-pointer technique. This is appropriate here because a palindrome reads the same forwards and backwards, which allo...
Approach
- Iterate through the array: For each element in the array, treat it as the potential center of a palindrome.
- Expand around the center: Use two pointers. One pointer starts at the center a...
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