← Perplexity Interview Insights
Got through the main logic fine, dedup first then figure out the order from the paragraphs.
Clarify the problem: deduplicate sources while preserving first occurrence, then reorder based on the order they appear across paragraphs. Propose an efficient algorithm using a hash set for deduplication and a hash map to track first occurrence positions, then sort by those positions. Discuss time/space complexity and edge cases.
Pro tip: Mention that the reordering should be stable and based on the first appearance across paragraphs, and that you can combine deduplication and ordering in one pass to avoid multiple iterations.
Ask about input format: are sources strings? Are paragraphs lists of sources? Confirm that deduplication should keep the first occurrence and that reordering is based on the earliest appearance across all paragraphs.
Use a hash set to track seen sources for deduplication. Use a hash map to store the first index where each unique source appears across paragraphs. Then sort the unique sources by that index.
Time complexity: O(N + M log M) where N is total sources and M is unique sources. Space: O(M). Mention that if paragraphs are already in order, you can collect unique sources in order without sorting.
Consider empty inputs, all duplicates, sources appearing in multiple paragraphs, and large datasets. Discuss stability and whether the original order of paragraphs matters.
Walk through a small example to verify correctness. Mention potential pitfalls like case sensitivity or whitespace differences if sources are strings.
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