Low-Level Design rounds show up from SDE-2 onward at Walmart, and cache-design prompts (LRU/LFU) reappear often enough to be worth practicing from scratch. Interviewers expect you to drive requirement clarification yourself and to be ready to defend any design pattern you reach for, not just name it.
Design a system for a restaurant that handles both table reservations and the order lifecycle from placement to serving. It should allocate tables to reservations, track an order from placed through preparing to served, and keep the booking and serving concerns cleanly separated so new order types can be added later without reworking the reservation flow.
Requirements to clarify first
- What makes a reservation valid — a fixed time slot (say 90 minutes) for a party size, or an open-ended booking that is released when the party leaves?
- How should table allocation behave under contention — does a reservation always beat a walk-in for the same table, and can two small tables be combined for a large party?
- Which staff roles need to exist in the model — is a waiter assigned per table, per order, or per shift — and does the kitchen need its own view of the order queue?
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The class design, entity list, design-pattern reasoning and follow-up discussion for these — plus the full worked solution above — are part of the Placement-Ready PYQ Kit.
1 more LLD prompts with full class designs in the full Placement-Ready PYQ Kit