SDE-2 at Google

How it went

What they would tell you

How to prepare

Round by round

1. 1

   Coding45 min

   Hey everyone, I wanted to take a moment to share my experience interviewing for an SDE-2 position at Google. To be honest, when I got that LinkedIn message from the recruiter, I was shocked and then super excited. This was the first real taste of the interview process. We connected on Google Meet, and the interviewer immediately put me at ease. He was professional but friendly, which made me feel comfortable right away. The problem he gave me was a matrix traversal problem with weighted paths, but with a twist: the weights could change depending on your previous path. Before jumping in, I made sure to clarify everything, like whether diagonal moves were allowed and what the size constraints were. It’s always good to clear those things up first, right? I started with a DFS approach, but quickly realized it was inefficient for this problem. I switched to Dijkstra’s algorithm with a priority queue, which seemed to work much better.

   • Matrix Traversal Problem with Weighted Paths
2. 2

   DSA60 min

   This round was intense. I won’t lie, I was nervous because it was a proper level 9/10 question. The problem involved designing a data structure that had to support dynamic updates, allow real-time range queries, merge intervals on-the-fly. I started with an approach, but as I wrote the code, I realized it wasn’t going to scale well for larger inputs. I quickly switched to using a TreeMap and discussed how it would work better for this problem. Although I didn’t finish all the code, I was able to explain my thought process clearly and mentioned what I would do if I had more time.

   • Dynamic interval Data Structure
3. 3

   System Design 160 min

   I was given the task to design a real-time transaction processing system for Google Pay. This is exactly the kind of system I love to design. We talked about throughput requirements, transaction types, failure guarantees, external payment gateways. I started sketching out my ideas:

   • Auth Gateway for user verification

   • Transaction Coordinator for managing the flow

   • Kafka for asynchronous validation

   • Idempotency tokens to prevent duplicate transactions We also discussed:

   • PCI zones for security

   • Data masking to protect sensitive information

   • Reconciliation jobs for consistency

4. 4

   Googliness / Behavioral42 min

   This was the round where they really wanted to get to know me. They asked:

   • “Tell me about a time you disagreed with a tech lead.”

   • “How do you handle pressure?”

   • “What’s one mistake you’ll never forget?” I didn’t try to sugarcoat anything. I shared stories about:

   • Stopping a risky prod release even though my manager was pushing for it

   • A time I accidentally pushed to master and had to fix it at 2 AM, adding CI checks the next day

   • Helping onboard a junior engineer and learning the importance of patience

5. 5

   System Design 260 min

   Surprise! Another system design problem. This one was designing a scalable notification system for Google Pay. The interviewer asked me to consider:

   • Push vs Email vs SMS notifications

   • FCM integration for push

   • Kafka for message distribution

   • Deduplication and prioritized queues for handling traffic spikes They asked questions like:

   • “How would you avoid flooding the same user with 5 notifications in 10 seconds?” I suggested:

   • Debounce windows

   • Mergeable payloads

   • Notification scheduler

   • Cache-based cooldowns The round felt more like a deep dive rather than a test. It was definitely an enjoyable discussion.

6. 6

   Hiring Manager Round45 min

   This was a more informal round with the hiring manager. She asked:

   • “What motivates you?”

   • “What frustrates you in engineering?”

   • “Why Google Pay?” I notified her:

   • I love building backend systems that are reliable and scalable. I get excited by the challenge of fixing failures.

   • I get frustrated when I work on systems that don’t have a real-world impact, that’s why I love working on systems like Google Pay.

   • I respect Google Pay because it’s real, and it actually matters to people. That connection really resonated with her.

What came up