Reddit prep

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

#01

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

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

Medium Read answer →

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

#02

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

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

Hard Read answer →

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

#03

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

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

Hard Read answer →

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

#04

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

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

Hard Read answer →

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

#05

Design a URL shortening service — Reddit interview

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

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

#06

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

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

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Reddit Mid-level (3–5 years) Behavioral

#07

Tell me about a time you disagreed with a teammate. How did you handle it? — Reddit interview

Reported in Reddit USA engineering loops. Behavioral STAR question assessing collaboration and conflict resolution.

Medium Read answer →

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

#08

What principles do you follow when designing RESTful APIs? — Reddit interview

Reported in Reddit USA engineering loops. API design question covering resources, HTTP semantics, and versioning.

Medium Read answer →

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

#09

When would you choose microservices over a monolith? — Reddit interview

Reported in Reddit USA engineering loops. Architecture trade-off question for mid-level backend and platform roles.

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

#10

Explain CI/CD and what a typical pipeline includes — Reddit interview

Reported in Reddit USA engineering loops. DevOps fundamentals for mid-level engineers discussing automation and quality gates.

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

#11

What is the difference between unit and integration tests? — Reddit interview

Reported in Reddit USA engineering loops. Testing strategy question covering pyramid, mocks, and confidence vs speed.

Easy Read answer →

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

#12

How does HashMap work internally in Java? — Reddit interview

Reported in Reddit USA engineering loops. Java-specific collections question on buckets, hashing, and resize behavior.

Medium Read answer →

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

#13

Explain the JavaScript event loop, call stack, and task queues — Reddit interview

Reported in Reddit USA engineering loops. Core JavaScript concurrency model question for frontend and Node.js roles.

Medium Read answer →

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

#14

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

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

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

#15

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

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

Medium Read answer →