- Status: SDE2 at Mid-sized Product Co.
- Experience: 3.5 Years
- Position: SDE2 (L61/L62)
- Location: India (Remote/Hybrid)
- Date: March 2026
Round 1: DSA & Problem Solving
- Question 1: LeetCode 124 (Binary Tree Maximum Path Sum).
- Question 2: (Similar to Trapping Rain Water 3d).
- Details: The interviewer was very focused on Edge Cases (e.g., all negative nodes in the tree). We spent the last 10 minutes discussing how to unit test these scenarios.
Round 2: Low-Level Design (LLD) / Machine Coding
- Task: Design a Task Scheduling System (like Cron/Airflow).
- Requirements:
- Support one-time and recurring tasks.
- Handle task dependencies (Task B starts after Task A).
- Thread-safety for concurrent execution.
- Focus: Used the Observer Pattern for status updates and a Directed Acyclic Graph (DAG) to model dependencies. Clean code and SOLID principles were a must.
Round 3: High-Level Design (HLD)
- Task: Design Microsoft Teams Messaging Infrastructure.
- Key Areas:
- Real-time delivery: WebSockets vs. Long Polling.
- Scalability: How to handle a group chat with 10k+ users?
- Storage: Partitioning strategy for chat history (NoSQL/Cassandra).
- Deep Dive: Discussed Sequence Numbers vs. Timestamps for message ordering in a distributed environment.
Round 4: AA (As Appropriate) / Hiring Manager
- Focus: Cultural fit and "Growth Mindset."
- Discussion:
- "Tell me about a time you mentored a junior and it didn't go well."
- "How do you handle technical debt when there is a deadline?"
- Technical: We had a brief discussion on microservices observability (tracing and metrics) to gauge my interest in the operational (“Ops”) aspects.
Final Verdict: Selected.
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