Microsoft | SDE-2 | India | Dec 2025 | Rejected

Round 1: DSA & Problem Solving (1 Hour)

This round ultimately cost me the offer. I faced two questions:

1. Permutation in String: I was quite nervous and unfortunately missed the optimal Sliding Window approach (Fixed size window). Instead, I implemented a Brute Force solution, generating all permutations of s1 (O(N!)) and checking their existence in s2. The interviewer expected an optimized solution immediately, which I realized was a major red flag for an SDE-2 role.
2. IP Address Management (LRU Cache Logic): I recovered well here. I explained my approach using a Doubly Linked List coupled with a HashMap, which is standard LRU logic. We had a detailed discussion on the time complexity for add, delete, and update operations. The Low-Level Design (LLD) discussion likely saved me from a harder rejection, but my coding in the first question was definitely a weak point.

Round 2: System Design & LLD (1 Hour)

This round involved a detailed discussion on projects from my resume, focusing on aspects like scaling and database choices. I felt very confident here, achieving what I believe was about 90% accuracy in my responses. The coding/LLD part required me to design a Cache Service with pluggable eviction strategies. I implemented the Strategy Pattern, creating a Cache class that accepts an EvictionType interface, and I fully coded the LRUEvictionStrategy. The interviewer seemed quite happy with the extensibility of my code.

Round 3: Senior Engineering Manager (1 Hour)

This round started with a deep dive into my current work projects. We drew out the architecture, and the manager was very satisfied with my answers regarding design trade-offs. For the coding part, I was asked about Bishop Moves on a Chessboard. Given coordinates (x, y) for a Bishop on an 8x8 board, I needed to print all valid moves. My initial thought was to use four separate while loops for each diagonal direction, but I quickly optimized it to a single loop using a direction array like [(-1,-1), (-1,1), (1,-1), (1,1)] to make the code cleaner and more maintainable.

Round 4: Engineering Manager (1 Hour)

This round was split into behavioral questions and a coding problem. The behavioral questions were standard: "Why are you looking for a change?" and "How do you handle work you don't like?". The coding question was Sort Colors, also known as Dutch National Flag, which required me to sort an array of 0s, 1s, and 2s without using a sort function and in O(1) space. I solved it using the classic 3-pointer approach (Low, Mid, High). Although I arrived at the correct solution, the interviewer mentioned that I "could have coded it faster."

My final verdict was a rejection. I cleared 3 out of 4 rounds positively, but it seems they had a strong pool of candidates who cleared all rounds, which led to me being dropped from the process. I felt disappointed, as the competition is incredibly tough nowadays.