Looked like a problem I'd seen before and almost just coded the standard approach without thinking about uniqueness.
Clarify the problem constraints (string vs. collection, condition type, expected output format) and discuss trade-offs between brute-force and optimized approaches. Use a hash set to deduplicate substrings while generating them, and consider algorithmic optimizations like sliding window or suffix automaton based on the condition. Analyze time and space complexity, and handle edge cases such as empty input or no matches.
Pro tip: At Citadel, interviewers value rigorous complexity analysis and awareness of performance bottlenecks. Explicitly compare the naive O(n^3) approach with optimized methods, and mention how deduplication with a hash set affects memory usage.
Ask questions to confirm the input type (string or collection), the exact matching condition, and the expected output format (e.g., list of unique substrings).
Outline a straightforward solution: generate all substrings, check the condition, and use a hash set to collect unique matches. Analyze its time and space complexity.
Propose an optimized approach based on the condition, such as sliding window for contiguous substrings or a trie/suffix automaton for pattern matching, while still deduplicating with a set.
Compare the time and space complexity of the brute-force and optimized solutions, and discuss trade-offs (e.g., memory vs. speed).
Mention edge cases like empty input, no matches, duplicate substrings, and large inputs, and explain how your solution handles them.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.