I had two simultaneous loops for two different positions at Microsoft and was selected for both. I ultimately accepted the one I thought was best suited for me.

The interview process began with an emailed questionnaire that included personal and problem-solving questions. Then, the loops themselves contained five interviews each. The interviewers were from the teams that needed candidates.

I was asked to comment on many actual scenarios and daily problems, along with their solutions. The 1:1 interviews mainly focused on algorithms and testing scenarios.

Overall, it was a typical Microsoft interview. The key to cracking it is to answer confidently and be strong in the fundamentals (data structures, algorithms).

Write a function that takes a phone number and outputs all possible alphabetical combinations (found on a standard phone keypad) for it.

How would you test this function?