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SAP·Software Engineer·Technical Phone Screen·Senior

Senior
Jun 2026

Summary

SAP data science interview with a system design question focused on anomaly detection for ship tracking. Pretty niche problem, felt like they wanted to see how you'd think through messy real-world data before jumping to any model.

Questions Asked (1)

Q1

Design a system that detects ships deviating from their expected course, given a dataset of position records as tuples of (ship_ID, x, y, z, timestamp) with irregular time intervals.

System DesignData ModelingAlgorithms & Data Structures
Author's notes

The irregular timestamps tripped me up more than I expected.

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AI HintsAI Generated

Suggested Approach

Start by clarifying requirements and assumptions (e.g., expected course definition, deviation threshold, real-time vs batch). Then propose a high-level architecture that ingests position records, handles irregular timestamps, computes expected paths, and detects deviations. Finally, dive into data modeling, algorithms, and scalability considerations.

Pro tip: Emphasize the importance of handling irregular time intervals by resampling or using interpolation, and discuss how to define 'expected course'—whether from historical patterns, planned routes, or predictive models. This shows you understand the data's nuances and avoid oversimplifying.

1. Clarify Requirements and Assumptions

Ask about data volume, latency requirements (real-time vs batch), definition of expected course, and what constitutes a deviation. Establish assumptions to scope the problem.

2. Design Data Ingestion and Storage

Propose a pipeline to ingest streaming or batch position records, store them in a time-series database or data lake, and handle irregular timestamps via interpolation or windowing.

3. Model Expected Course and Deviation Detection

Define expected course using historical trajectories, route plans, or predictive models. Compute deviation metrics (e.g., distance from expected path, heading change) and set thresholds.

4. Implement Detection Algorithm

Choose algorithms (e.g., clustering, Kalman filters, LSTM) to predict expected positions and compare with actuals. Handle irregular intervals by resampling or using time-aware models.

5. Address Scalability and Operational Concerns

Discuss scaling with distributed processing (e.g., Spark, Flink), alerting mechanisms, and monitoring. Consider false positives and feedback loops.

Key Points to Mention

  • Handling irregular time intervals: interpolation, resampling, or time-aware models
  • Defining expected course: historical patterns, planned routes, or predictive models
  • Deviation metrics: distance from expected path, heading change, speed anomalies
  • Choice of algorithms: clustering, Kalman filters, LSTM, or rule-based
  • Scalability: distributed processing (Spark, Flink), time-series databases
  • Alerting and false positive management: thresholds, feedback, and monitoring

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