I submitted my resume at a career fair. I was subsequently invited to an on-campus interview with a recruiter who had previously worked as a PM. The interview was non-technical; he only asked about my previous work and which of the three internship types I was considering.

One week later, I was invited to fly down to Redmond. Microsoft paid for the flights, sightseeing expenses, and a generous amount of food.

The onsite interview itself was four rounds.

The first round was a standard dynamic programming problem: maximum-sum subarray.

The next two rounds were tailored to my expressed interest in machine learning, and involved implementing the k-means algorithm and a predictive progress bar.

The final round was with the team lead, who asked a very trivial coding problem and talked more about the position.

Previous reviews mentioned receiving an offer on the spot, which worried me when I was let go without a word. I received a phone call five days later with an offer.

How would you implement the "estimated time to completion" feature of a progress bar?