This was for the Office 365 team. I was invited to attend a full-day interview at their campus in Hyderabad. I arrived at 9 AM and left at 5 PM.

I was interviewed by four interviewers, all from the Office team. I could sense they were all very knowledgeable and quite senior.

Each of them was very courteous and took a good amount of time analyzing my expertise in the specific areas they were interviewing on.

The first round was problem-solving. The interviewer, a senior engineer, was very specific about the code written, the edge cases, the readability, and the extensibility of the code. They checked how I would extend the code for a more generic problem. Some brushing up on design patterns would have helped here. This round took around 45 minutes.

The second round was a mix of low-level design, data structures and algorithms, and high-level design. The interviewer was a mid-level engineer, very friendly, and this round felt more or less like a friendly discussion. It ended with a data structure problem where I was asked to write code on paper. This took about 1 hour.

The third round was mostly high-level design, conducted by an ex-Googler and Principal Engineer. They were brilliant! We dug very deep into the intricacies of designing the system for the given problem. This round actually sealed it for me that I need to join this team. It took around 1 hour.

The fourth and final round was likely with the hiring manager. Again, a very technical interview on various aspects ranging from data structures, algorithms, low-level design, and high-level design. They took more time than the others.

Here's the text to clean up:

• Implement a queue using an array in a circular fashion (if the end is reached, add to the start of the array if free).
• Perform circular traversal of a 2x2 matrix.
• Find the max continuous increasing sequence in a given Binary Tree.
• Design a graph API.
• Design API throttling.
• Design a multi-game, multi-player service using a single-threaded machine.
• Sort a big file of integers using limited memory.