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rippling·Software Engineer·Technical Phone Screen·Intermediate

Intermediate
Jun 2026

Summary

Rippling SWE interview had a follow-up coding question that was more nuanced than it first appeared.

Questions Asked (1)

Q1

Implement a get_top_k(k) function where each upvote adds +1 and each downvote subtracts 1 from an article's score, and you return the top k articles by score.

Algorithms & Data Structures
Author's notes

Seemed straightforward until I started thinking about whether to sort every time or maintain a heap.

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AI HintsAI Generated

Suggested Approach

Clarify the requirements: whether scores update dynamically and if get_top_k is called frequently. Then propose a data structure that supports efficient score updates and top-k queries, such as a hash map for scores combined with a heap or balanced BST. Discuss trade-offs between different approaches and analyze time/space complexity.

Pro tip: Mention that if get_top_k is called frequently, you can maintain a sorted structure or cache the top-k results, but be prepared to discuss the trade-off between update and query performance. Also, consider using a min-heap of size k for O(n log k) top-k selection when k is small.

1. Clarify requirements

Ask whether scores are updated in real-time and how often get_top_k is called. Determine if k is fixed or variable, and if ties need special handling.

2. Choose data structures

Propose using a hash map to store article scores for O(1) updates. For top-k queries, consider a heap, balanced BST, or sorting depending on frequency.

3. Design algorithm

For each get_top_k call, if using a heap, iterate through all articles and maintain a min-heap of size k. Alternatively, maintain a sorted list or use a quickselect algorithm.

4. Analyze complexity

Discuss time and space complexity: O(1) update, O(n log k) for heap-based top-k, or O(n) average with quickselect. Compare with maintaining sorted order O(log n) update and O(k) query.

5. Handle edge cases

Consider k larger than number of articles, negative scores, ties, and concurrency if updates and queries happen simultaneously.

Key Points to Mention

  • Hash map for O(1) score updates
  • Min-heap of size k for O(n log k) top-k selection
  • Trade-offs between update and query performance
  • Quickselect for O(n) average time top-k
  • Handling ties and k > n
  • Concurrency and thread safety if needed

AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.