One of my colleagues from a previous company at Microsoft has referred me for the SDE-1 position. And a month later they have called me and asked if I was available for an interview, and they scheduled 3 rounds of interviews on the same day with a week gap. On that day, I had 3 interviews of 1 hour long with some breaks in between. All the interviews happened online due to the pandemic situation.
1st Round: Had some small chit-chat regarding how Work from Home is going on for him and me. Later he introduced himself and asked the same.
Then he gave me the last 5 mins to ask any questions to him.
2nd Round: This round started without any introduction, and he directly jumped into the question. Asked me about the algorithm, and later coded it and ran it. And then he asked me to optimize it. Finally, he asked me if I had any questions.
3rd Round: This was the last round of the day. He introduced himself and asked how I reduced API response times(which I mentioned in my resume). We discussed it for 5-10 min. Then he asked about the project(can’t share those details here) which I worked on in my prev company. Discussed use cases and complete design of the implementation. Then, he asked me a question which is similar to System Design. Finally, he asked me if I had any questions.
After these 3 interviews, that night, HR called and informed me that I was selected for the 4th and final round. He scheduled a meeting for 4 days later.
Final Round: He started off by asking me to open my mobile phone and told me to open any messaging application and type something. Then, he pointed out to look at the suggestions after and while typing a word. Then, he asked me to design that functionality for a newly bought mobile. There are multiple ways to do it using Tries and Ternary Search Tree, we discussed some of them and one in-depth. Later, he asked me about Distributed File Systems and why and when they are used. And also about how the Single Point of Failure issue handled. By this time almost 50 min was completed. Then, he asked me to write the code for Sudoku solver. I explained the algorithm and gave a walkthrough, and he was convinced. But, when I ran it the test cases were not passing due to a very small bug. This round happened for around 1 and a half hours.
Almost a week later, I received a call from Microsoft telling me that I was selected. I was more than happy. This is like dream come true for me.