SDE2 Interview Questions at Swiggy

Design Swiggy's real-time order tracking system. A customer should see their delivery agent's location update every 5 seconds on a map. Cover: location ingestion from agents, WebSocket vs SSE for pushing updates to clients, data store choices, and how you scale to 100k concurrent orders during peak hours.

Design Swiggy's delivery partner assignment algorithm. When an order is placed, how do you assign the optimal nearby delivery partner within 2 minutes considering distance, current load, and restaurant prep time?

Design Swiggy's notification system. When an order status changes (Confirmed, Picked Up, Arriving), send push notification, SMS, and in-app notification reliably with at-least-once delivery. Cover fan-out and handling inactive devices.

Design Swiggy's restaurant search and ranking system. How do you index 200k restaurants? Discuss full-text search (Elasticsearch), geospatial filtering, personalised ranking signals (past orders, ratings, delivery time), and how to refresh the index when a restaurant updates its menu.

Design the data model for Swiggy's menu system. A restaurant has categories, items, add-ons, variants, and availability windows (breakfast/lunch/dinner). How do you model this in PostgreSQL and handle real-time menu updates?

Tell me about a time you had to make a quick technical decision with limited information. How did you validate the decision afterwards? What would you do differently?

You need a collection that maintains insertion order AND gives O(1) lookup by key. Which Java collection would you use, and why not a plain HashMap?