Fumbled up : Microsoft SDE 2

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sde 2No Offer
November 29, 2025109 reads

Summary

I interviewed for an SDE 2 position at Microsoft through a hiring drive. Despite putting in effort, I struggled with several coding challenges and system design questions across two technical rounds, ultimately leading to an unsuccessful outcome.

Full Experience

I applied for an SDE 2 position on the Microsoft career page and subsequently received an invitation for a hiring drive on November 28th.

Round 1

My first interviewer was an SDE-2 with 4 years of experience. This round primarily focused on data structures, algorithms, and operating system fundamentals.

  1. Two Sum in BST: I was asked to determine if two elements exist in a given BST such that their sum equals k. My approach involved an inorder traversal followed by a two-pointer technique, which gave an O(n) time complexity and O(n) space complexity. The interviewer, however, was looking for a solution using a BST Iterator to achieve O(n) time and O(h) space complexity, where h is the height of the BST.
  2. Longest Repeating Character Replacement: The problem involved finding the length of the longest substring in a given uppercase English letter string s that could be transformed into a substring containing only one distinct character by changing at most k characters. This is LeetCode 424. I struggled to fully code this, but with hints, I was able to outline the sliding window solution.
  3. OS Fundamentals: The interviewer also delved into operating system concepts, asking about:
    • TCP vs UDP
    • Virtual Memory
    • Process vs Threads
    • What is Throughput, Bandwidth and Latency?

Round 2

The second interviewer was an SDE-2 with 9 years of experience. This round had a mix of questions related to my resume, system design concepts, and another LeetCode problem.

  1. Resume and System Design Discussion: We started with questions based on my resume, leading into discussions on:
    • What is Async?
    • Questions on OAuth, JWT Token.
    • What is Docker, container, Image?
    • Sidecar architecture.
    • Types of containers.
    • Pipelines.
  2. LeetCode 1309 – Decrypt String from Alphabet to Integer Mapping: I had a really hard time with this problem and fumbled up big time.
  3. Maximum Subarray Sum with Length at Most K: I was given an array profits[] where positive values indicated profit and negative values indicated loss. The task was to find the maximum possible sum of a contiguous subarray whose length is less than or equal to k. Despite receiving hints, I couldn't come up with the correct solution for this problem.

Overall, I felt I fumbled in several key areas during the interview process.

Interview Questions (14)

Q1
Two Sum in BST
Data Structures & AlgorithmsMedium

Given a Binary Search Tree (BST) and an integer k, return true if there exist two elements in the BST such that their sum equals k, otherwise return false.

Q2
Longest Repeating Character Replacement
Data Structures & AlgorithmsMedium

Given a string s consisting of uppercase English letters (A–Z), and an integer k, return the length of the longest substring that can be transformed into a substring containing only one distinct character by changing at most k characters.

Q3
TCP vs UDP
Other

Explain the key differences between TCP (Transmission Control Protocol) and UDP (User Datagram Protocol).

Q4
Virtual Memory
Other

What is virtual memory and how does it work?

Q5
Process vs Threads
Other

Differentiate between a process and a thread.

Q6
Throughput, Bandwidth, and Latency
Other

Define Throughput, Bandwidth, and Latency in the context of computer networks.

Q7
What is Async?
Other

Explain what asynchronous programming is and its benefits.

Q8
OAuth and JWT Tokens
System Design

Discuss OAuth and JWT (JSON Web Token) tokens, explaining their purpose and how they are used.

Q9
Docker, Container, and Image
System Design

Explain the concepts of Docker, containers, and images, and how they relate to each other.

Q10
Sidecar Architecture
System Design

Describe the Sidecar architecture pattern.

Q11
Types of Containers
System Design

What are the different types of containers?

Q12
Pipelines
System Design

Explain the concept of pipelines in software development/DevOps.

Q13
Decrypt String from Alphabet to Integer Mapping
Data Structures & AlgorithmsEasy

LeetCode problem 1309: Given a string s that contains only digits ('0'-'9') and the '#' character, decode the string into English lowercase letters.

Q14
Maximum Subarray Sum with Length at Most K
Data Structures & AlgorithmsMedium

Given an array profits[] of size n where profits[i] > 0 indicates a month had profit and profits[i] < 0 indicates a month had loss, find the maximum possible sum of a contiguous subarray whose length is less than or equal to k.

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