A

Amazon

Hard
22Challenges
4War Rooms
~45hPrep Time
3/22Completed

LP-heavy. Every interview maps to Leadership Principles. Own your execution.

14% complete
Interview rounds:OACoding ×2System DesignBehavioral (LPs) ×2

DSA4

Distributed Hash Ring — Consistent Hashing (Binary Search)Building a distributed Redis cache. When a node is added, map user IDs to servers using Co…
Senior~45 min
Packet Data Compression (Sliding Window)Given a string `s`, find the length of the longest substring without repeating characters.…
Mid~30 min
Cross-Sell Recommendation Scoring (Prefix/Suffix Arrays)Given an integer array `nums`, return an array `answer` such that `answer[i]` is equal to …
Mid~30 min
Promotion Bundling (Combination Sum)Given an array of distinct integers `prices` and a target integer `target`, return a list …
Mid~45 min

PR Review1

Optimistic Locking FailureIn a high-traffic "Edit Product" screen, users are complaining that their changes are "van…
Mid~15 min

War Room4

Cascading Failure via Synchronous CallsThe non-critical "Recommendations" service slowed down. Suddenly, the critical "Checkout" …
Senior~30 min
Redis maxmemory Evicting Hot Keys Mid-TrafficUsers are being randomly logged out. Customer support tickets are flooding in. Redis memor…
Mid~20 min
DynamoDB Hot Partition ThrottlingLyft's ride request API is throwing ThrottlingException from DynamoDB during a surge event…
Mid~25 min
Log4Shell Zero-Day in Production JVM ServicesIt's December 10, 2021. A critical 0-day (Log4Shell) is publicly disclosed affecting Log4j…
Senior~30 min

System Design6

Design a Key-Value Store (Redis)Design a distributed key-value store that supports GET, PUT, DELETE with sub-millisecond l…
Mid~50 min
Design a Distributed Message Queue (Kafka)Design a durable, distributed message queue that supports 1M messages/sec write throughput…
Senior~55 min
Design an Ad Click Aggregation SystemDesign a system to count ad clicks for billing and analytics. Ad networks must know clicks…
Senior~55 min
Design a Flash Sale SystemDesign a flash sale system: 1000 PS5 consoles go on sale at exactly 9:00 AM. 500,000 users…
Senior~55 min
Design a Recommendation EngineDesign a recommendation engine for a streaming platform. Recommend the top-10 most relevan…
Senior~55 min
Design Amazon (E-Commerce Checkout)Design Amazon's checkout and order processing flow. A customer adds items to cart, proceed…
Senior~55 min

Tech Debt Tribunal3

Refactor the God Class (AuthManager)AuthManager.java is a 4,000-line file with a massive if/else chain for Email, Google, Appl…
Mid~45 min
Missing Circuit Breaker on Downstream ServiceA checkout service calls a loyalty points API synchronously. When the loyalty service degr…
Senior~35 min
String Template Literals Over Array JoinAn email template builder concatenates 50+ lines with string interpolation in a loop, crea…
Junior~15 min

War RoomAmazon-specific4

S3 Presigned URL Expiry BugA presigned URL TTL was accidentally set to 5 seconds instead of 5 minutes in a recent Lam…
P1+1100 XP
DynamoDB Hot PartitionBlack Friday traffic is hammering a single DynamoDB partition key. Checkout latency is 14x…
P0+1600 XP
SQS Message Deduplication FailureSQS message deduplication is failing on a FIFO queue. Payment processing is double-chargin…
P0+1500 XP
Lambda Cold Start CascadeA surge of cold starts after an idle period is causing cascading timeouts across a Lambda …
P2+850 XP