How I Got an SDE 2 Offer at Booking.com

Role: Software Development Engineer II (SDE 2)

Location: Amsterdam, Netherlands

Preparing for technical interviews while managing a full-time role is no easy feat, but hard work pays off.

Round 1: Recruiter Screening (60 mins)

This was an introductory conversational round with the recruiter focused on my background and culture alignment:

• My past engineering experience, key achievements, and project leadership.

• Discussion around my motivations for joining Booking.com and relocating to Amsterdam.

Tip: Be prepared to highlight impact metrics and specific ownership roles in your past projects.

Round 2: DSA

The interview lasted around one hour and focused on problem-solving and optimization.

Question: Maximum Number of Transactions Within a Time Window

I was given an array of integers representing the timestamps of transactions and an integer K representing a time window.

I had to find the maximum number of transactions that occurred within any continuous time window of length K.

Example:

timestamps = [1, 2, 3, 5, 6, 8, 10, 11]
K = 3

Output:

3

Explanation:

The time window from 1 to 3 contains three transactions: 1, 2, 3.

No other window of length 3 contains more transactions.

I approached this problem using the sliding window technique, maintaining a window of valid timestamps and updating the maximum count as I moved through the array.

I also discussed the time and space complexity and walked through the solution with an example.

Round 3: System Design (90 mins)

An interactive architecture and system design session centered around backend scalability, real-time data, and high concurrency.

• Problem Statement: Design a Food Delivery System, with a deep dive into rider-to-user order delivery dynamics.

• Key Technical Topics Covered:

  • Proximity Search: Evaluating Spatial Indexing (Geohash / Quadtrees / Uber H3) vs. Redis Geospatial queries for tracking active driver locations in real time.

  • Concurrency Control: Utilizing Optimistic Concurrency Control (OCC) to prevent race conditions during driver assignment and order state transitions.

  • Messaging & Data Flow: Leveraging Kafka for reliable event streams (order events, status tracking) and Redis for low-latency state caching.

Experience: Very collaborative whiteboard discussion. The interviewer engaged deeply in trade-off discussions, making it a great experience.

Round 4: Cultural & Behavioral Fit (60 mins)

This round evaluates leadership, collaboration, product mindset, and conflict management.

• Project Deep Dive:

  • Detailed discussion on my most recent high-impact project.

  • Crucial note: Pick a project where you had clear architectural and execution ownership. Expect heavy follow-ups on your exact contribution, how you drove architectural decisions, and how you built consensus across teams.

• Product & Experimentation:

  • Multiple questions centered around A/B testing, feature rollout strategies, metrics evaluation, and handling unexpected experiment outcomes.

• Soft Skills:

  • Scenario-based questions on cross-functional conflict resolution, handling technical debt vs. feature deadlines, and stakeholder management.