Affirm Software Engineer Interview Experience — One-Hour Tech Screen With a Debugging Part and a Suspicious-Data Detector

Two interviewers, one of them shadowing, one hour in total.

The questions looked like they came from the HackerRank Affirm question bank. It was split into two parts, and both had test cases you could use to check that your code was correct.

The first part was debugging. The background was roughly counting the number of unique entities in a data stream. You could work out the approach from the problem description and the sample cases.

The second part was implementing a piece of code, with background related to the first part. I had to write a method that detects suspicious data. Different event types in the stream are handled differently: if it is a flagged type, you store it and use it to process future data; if it is a regular event, you check its key-values to decide whether it is suspicious, and you also store the other key-values and use them when processing future data.

After each part was done, they asked some maintainability-related questions. At the start of the interview you are asked to share your entire screen, probably to prevent cheating.