My resume was shortlisted through a LinkedIn referral.
The first round was largely conversational and focused on core CS fundamentals rather than heavy coding.
I was asked about Linked Lists, including their real-world applications, how they compare with arrays, and in which situations one would prefer linked lists over arrays. This then transitioned into questions on HashMaps, where I was asked how they store unique elements internally and to explain the concept of hashing at a high level.
I was then asked- how to store elements uniquely.
I suggested using a HashMap, after which a constraint was introduced—to solve it without using any additional data structure. We discussed alternative approaches, and I explained a sorting followed by linear comparison solution.
Overall, the round felt more focused on understanding trade-offs and different approaches rather than arriving at a single “optimal” answer.
The second round started with a design-oriented problem involving users and groups.
The initial requirement was to design a data structure where:
A user can belong to multiple groups
We should be able to fetch:
(i) all groups a user belongs to
(ii) all users in a given group
HashMap usage was initially not allowed.
I discussed multiple approaches- connected graph based approach, using adjacency representations, and reasoning about DSU. The emphasis was clearly on explaining design choices, complexity, and scalability. For every design suggested, cross-questions on its scalability were fired.
After the discussion, I was then asked to code the solution with HashMaps allowed. I focused on writing modular code while explaining my approach.
Overall Takeaway
The entire interview process was fundamentals-driven, with strong emphasis on data structure understanding, and design thinking. Microsoft values how well you can explain why a solution works just as much as how you implement it.
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