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rippling·Software Engineer·Onsite - Coding / Algorithms·Intermediate

IntermediatePrefer not to say
Jul 2026

Summary

Rippling software engineer coding round with two back-to-back implementation problems. The logger one was more open-ended than it looked, and the card game problem had a wildcard extension that I didn't fully finish.

Questions Asked (2)

Q1

Design and implement a configurable logger that supports message transformation behaviors like substring removal, truncation, uppercase conversion, and in-memory storage, with a search feature over stored messages.

System DesignTechnical Trade-offsAlgorithms & Data Structures
Author's notes

Looked deceptively simple at first.

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AI HintsAI Generated

Suggested Approach

Start by clarifying requirements and defining a clean interface for the logger with pluggable transformation behaviors. Then design the data structures and algorithms for efficient storage and search, discussing trade-offs between simplicity and performance. Finally, walk through an implementation sketch, covering edge cases and extensibility.

Pro tip: Emphasize the Strategy pattern for transformations and the importance of immutability and thread-safety in a logging system. Also, discuss how you would test each transformation and the search functionality.

1. Clarify Requirements and Scope

Ask questions to understand expected message volume, concurrency needs, search complexity, and whether transformations are applied at log time or query time. Clarify if transformations are composable and configurable at runtime.

2. Design the Logger Interface and Transformation Pipeline

Define a Logger interface with methods like log(message) and search(query). Use the Strategy pattern for transformations, allowing them to be composed in a pipeline. Consider a builder or configuration object to specify which transformations to apply.

3. Choose Data Structures for Storage and Search

For in-memory storage, consider a list for simplicity or a more advanced structure like an inverted index for efficient substring search. Discuss trade-offs: list with linear scan vs. trie or suffix tree for faster search at the cost of memory and complexity.

4. Implement Transformations and Search

Implement each transformation as a class with a transform method. For search, implement a method that iterates over stored messages (or uses an index) and returns matches. Ensure transformations are applied before storage if they are log-time, or during search if query-time.

5. Discuss Trade-offs, Extensibility, and Testing

Talk about performance vs. simplicity, thread-safety (e.g., using concurrent collections or locks), and how to add new transformations without modifying existing code. Outline a testing strategy for transformations and search.

Key Points to Mention

  • Strategy pattern for pluggable transformations
  • Composability of transformations (e.g., chain of responsibility or pipeline)
  • Trade-offs between different search algorithms (linear scan vs. inverted index)
  • Thread-safety and concurrency considerations
  • Configuration mechanism (e.g., builder, JSON config)
  • Testing approach for transformations and search

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

Q2

Implement a five-card hand ranker for a simplified card game: parse hand and bid records, categorize each hand, sort from weakest to strongest, and compute a weighted score. Optionally add a wildcard mode where J acts as the best possible rank for category purposes but the lowest for tiebreaking.

Algorithms & Data StructuresTechnical Trade-offs
Author's notes

The base problem was fine.

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AI HintsAI Generated

Suggested Approach

Start by clarifying requirements and edge cases, then outline a modular design: parse input, evaluate hand category, sort hands, and compute weighted score. Emphasize extensibility for wildcard mode and discuss trade-offs between simplicity and performance.

Pro tip: Demonstrate foresight by discussing how to handle the wildcard mode without duplicating logic—e.g., parameterize the hand evaluation to treat J as wild. Also, mention that sorting stability matters when hands have equal ranks.

1. Clarify Requirements and Edge Cases

Ask about input format, hand size, card ranks/suits, and tiebreaking rules. Confirm wildcard behavior: J acts as best rank for category but lowest for tiebreaking.

2. Design Data Structures and Parsing

Define a Hand class with cards, bid, and computed rank. Parse input into hands, validating format and handling errors.

3. Implement Hand Evaluation

Write a function to categorize a hand (e.g., five-of-a-kind, straight flush, etc.). For wildcard mode, treat J as wild and compute the best possible category.

4. Sort Hands and Compute Score

Sort hands by category and tiebreakers (with J as lowest in wildcard mode). Compute weighted score by multiplying bid with rank position.

5. Test and Optimize

Write unit tests for edge cases (e.g., all wilds, multiple wilds). Discuss time complexity and potential optimizations.

Key Points to Mention

  • Modular design: separate parsing, evaluation, sorting, and scoring for maintainability.
  • Wildcard handling: parameterize evaluation to avoid code duplication; consider all possible substitutions for J.
  • Tiebreaking rules: define a consistent comparison function, especially when J is wild.
  • Sorting stability: ensure stable sort if hands have identical ranks to preserve input order.
  • Time complexity: O(n log n) for sorting, O(1) per hand evaluation (since hand size fixed).
  • Testing: cover edge cases like multiple wilds, straight flushes with wilds, and invalid inputs.

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