Phone Screening (VP Round)
Duration: ~15 minutes

The VP briefly reviewed my resume, focusing on my experience with notification services (a key requirement for the role).

Assessed my knowledge in relevant areas but did not dive deep.

Shortly after, I was scheduled for the technical rounds.

Technical Round 1 (DSA Focused)
Introduction: Brief discussion about my background.

Problem 1: https://leetcode.com/problems/merge-intervals/description/ (LeetCode)

Problem 2: Find the duplicate in an array of size n with elements in [0, n-1].

Expected solution: Efficient swapping approach (similar to https://leetcode.com/problems/find-the-duplicate-number/description/).

Technical Round 2 (Resume Deep Dive + DSA)
First 30 mins: In-depth discussion on my resume, covering:

Redis Cache (eviction policies, clustering)

Kafka (consumer groups, partitioning, offset management)

REST API Security (OAuth 2.0, JWT, rate limiting)

High-level system design aspects of past projects.

DSA Problems:

Problem 1: Validate parentheses in a string (basic () case).

Follow-up: Extended to multiple types ((), [], {}).

Problem 2: Given an employee hierarchy (tree structure), find all reports under each manager.

Follow-up: Reverse lookup (find all managers for a given employee).

Technical Round 3 (Resume Grilling + Coding)
Resume Discussion: Focused on my experience with:

Email Notification Service (SMTP, DLQ handling)

Kafka (message retries, ordering guarantees)

Blue-Green Deployment (strategies, advantages)

High availability, throughput, and latency optimizations.

Coding Problem: Multiply two very large integers represented as strings (e.g., "123456789" * "987654321").

Constraints: No use of BigInteger or language libraries—had to implement manual multiplication.

Final Discussion & Offer
After clearing all rounds, had a follow-up call with the VP within a day to discuss:

Project alignment

Salary expectations

Background verification (BGV) process

Final Verdict: Hired!

Offer details: https://leetcode.com/discuss/post/6893969/oracle-pmts-bangalore-by-anonymous_user-j50z/