I applied through their website and received a call from HR within a few days.

They sent me a coding assignment and asked me to submit my solution within a week, although the email suggested it would only take a few hours.

The assignment involved developing an application capable of reading two column-formatted files (CSV) and performing simple mathematical and set operations on selected columns based on user input.

I implemented a solution using a stack, allowing for chained operations, even though they only requested single operations like c1 + c2 or c1 - c2. I felt my solution was quite good.

When I received the call for the technical interview, the coding assignment was not discussed at all. It seemed the interviewer had not had time to review my solution.

Instead, he asked very specific questions about C++ polymorphism implementation, particularly concerning vtables and their modification. I did not possess that level of depth in the language, and I suspect that was the reason for their dissatisfaction.

I wouldn't describe the interview as difficult; they didn't ask anything about algorithms or data structures, nor did they request any coding. The questions were purely theoretical.

Some in-depth questions about polymorphism in C++