← Back to Directory

Cognitiv

Small

Cognitiv is an advertising technology company that uses deep learning and artificial intelligence to power programmatic media buying and campaign optimization. It helps marketers build custom algorithms to improve the performance of their digital advertising.

2 interview notes · updated Jul 2026

Cognitiv·Machine Learning Engineer·Technical Phone Screen

Jun 2026
Cognitiv ML Engineer interview had a classic streaming median problem with a follow-up that actually made me think harder than the main question. Pretty algorithmic for an ML role, but not surprising given the company.
  • Design a data structure that accepts integers one at a time and returns the current median after each insertion. Implement add(x) and getMedian() operations, and analyze the time complexity of your solution.
  • Follow-up: if the full input is available upfront and you want to minimize auxiliary memory usage, how would you find the median without the extra space overhead of the two-heap approach?

“Two heaps, one max-heap for the lower half and one min-heap for the upper half.”

View Post

Cognitiv·Machine Learning Engineer·Onsite - System Design / Architecture

Jun 2026
System design round at Cognitiv for an MLE role. The whole thing was focused on a feature store for ads/recommendation ranking, which sounds scoped until you realize they want you to cover online serving, offline training, streaming ingestion, backfills, and monitoring all in one go.
  • Design a real-time feature store for ML systems used in ads or recommendation ranking, supporting both low-latency online inference and offline training with point-in-time correctness.
  • What APIs and abstractions should a feature store expose to its consumers?
  • How would you keep online and offline feature pipelines consistent with each other?
  • How do you handle fresh streaming features, backfills for historical data, and late-arriving events?
  • How would you scale the feature store and monitor data quality and reliability?

“This is the kind of question where you think you have a plan and then five minutes in you realize you've been drawing boxes without actually answering anything.”

View Post