Company interview vault

Instacart Mid-level (3–5 years) System design

#2596

Design a distributed rate limiter for an API gateway — Instacart interview

Reported in Instacart USA engineering loops. System design testing token bucket, sliding window, and Redis coordination.

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Instacart Mid-level (3–5 years) System design

#2597

Design a URL shortening service — Instacart interview

Reported in Instacart USA engineering loops. Foundational system design covering APIs, encoding, storage, and read-heavy scaling.

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Instacart Mid-level (3–5 years) Coding / DSA

#2598

Explain and implement Dijkstra's algorithm for shortest paths — Instacart interview

Reported in Instacart USA engineering loops. Graph algorithm for non-negative edge weights using priority queue.

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Instacart Mid-level (3–5 years) Coding / DSA

#2599

Solve the 0/1 knapsack problem with dynamic programming — Instacart interview

Reported in Instacart USA engineering loops. Classic DP testing tabulation, space optimization, and item selection reconstruction.

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Instacart Mid-level (3–5 years) Coding / DSA

#2600

Design and implement an LRU cache with O(1) get and put — Instacart interview

Reported in Instacart USA engineering loops. Hash map plus doubly linked list problem bridging DSA and system components.

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Instacart Mid-level (3–5 years) Coding / DSA

#2601

How many distinct ways can you climb n stairs taking 1 or 2 steps at a time? — Instacart interview

Reported in Instacart USA engineering loops. Introductory dynamic programming problem isomorphic to Fibonacci.

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DoorDash Mid-level (3–5 years) System design

#2602

Explain the CAP theorem and what it means for distributed systems — DoorDash interview

Reported in DoorDash USA engineering loops. Classic system design question asked at US big-tech and fintech on-site loops.

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DoorDash Mid-level (3–5 years) Coding / DSA

#2603

How do you perform topological sort on a directed acyclic graph? — DoorDash interview

Reported in DoorDash USA engineering loops. Graph algorithm for task scheduling, build systems, and course prerequisites.

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DoorDash Mid-level (3–5 years) Technical deep dive

#2604

What is dependency injection and why is it useful? — DoorDash interview

Reported in DoorDash USA engineering loops. Java/Spring staple connecting OOP design to testable service architecture.

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DoorDash Mid-level (3–5 years) Technical deep dive

#2605

How do you version a public API without breaking clients? — DoorDash interview

Reported in DoorDash USA engineering loops. API evolution question covering compatibility, deprecation, and communication.

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DoorDash Mid-level (3–5 years) Behavioral

#2606

Tell me about a project that failed or missed its deadline. What did you learn? — DoorDash interview

Reported in DoorDash USA engineering loops. Behavioral question testing accountability, retrospectives, and growth.

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DoorDash Mid-level (3–5 years) Technical deep dive

#2607

Compare ACID and BASE consistency models in databases — DoorDash interview

Reported in DoorDash USA engineering loops. Distributed data question bridging SQL transactions and NoSQL eventual consistency.

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DoorDash Mid-level (3–5 years) Technical deep dive

#2608

How does Node.js handle concurrent requests with a single thread? — DoorDash interview

Reported in DoorDash USA engineering loops. Node.js architecture question on libuv, event loop phases, and worker threads.

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DoorDash Mid-level (3–5 years) Technical deep dive

#2609

When would you use useState versus useReducer in React? — DoorDash interview

Reported in DoorDash USA engineering loops. React hooks question on local state complexity and predictable updates.

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DoorDash Mid-level (3–5 years) Technical deep dive

#2610

What is the Python GIL and how does it affect concurrency? — DoorDash interview

Reported in DoorDash USA engineering loops. Python-specific question on threading limits and multiprocessing alternatives.

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