Practice
Problems
Sandboxed coding rounds that run against a hidden test suite, and written questions graded against a rubric. Both, in one list.
72 problemsClear filters
| Status | Problem | Format | Level |
|---|---|---|---|
| Not started | Find a pair summing to a target, in a sorted arrayarraystwo-pointers | Written | easy |
| Not started | Auth Middleware Bug | Written | medium |
| Not started | Bounded producer-consumer queuec++concurrencycondition-variablequeues | Written | medium |
| Not started | Circuit Breaker | Written | medium |
| Not started | Connection Pool | Written | medium |
| Not started | CORS Mystery | Written | medium |
| Not started | Design a notification servicehldqueuesreliabilitysystem-design | Written | medium |
| Not started | Design a rate limiterconcurrencyhldreliabilitysystem-design | Written | medium |
| Not started | Design a retry policydistributed-systemslldreliability | Written | medium |
| Not started | Design a text-sharing servicecachinghldstoragesystem-design | Written | medium |
| Not started | Design a URL shortenercachinghldstoragesystem-design | Written | medium |
| Not started | Design a URL shortenercachingstoragesystem-design | Written | medium |
| Not started | Design an LRU cachecachingconcurrencydata-structureslld | Written | medium |
| Not started | Design notification fan-outfan-outqueuessystem-design | Written | medium |
| Not started | Design search autocompletecachingdata-structureshldsystem-design | Written | medium |
| Not started | Find the gapsgaps-and-islandssqlwindow-functions | Written | medium |
| Not started | Flaky Clock Test | Written | medium |
| Not started | Idempotent Payment API | Written | medium |
| Not started | Index Zero Doesn't Exist | Written | medium |
| Not started | Infinite Retry | Written | medium |
| Not started | Kth largest in a streamheapstreamingtop-k | Written | medium |
| Not started | Last Item Missing | Written | medium |
| Not started | Longest run of distinct elementshash-mapsliding-windowstrings | Written | medium |
| Not started | LRU Cache | Written | medium |
| Not started | Merge overlapping intervalsgreedyintervalssorting | Written | medium |
| Not started | Mocking Too Much | Written | medium |
| Not started | Mutable Default Nightmare | Written | medium |
| Not started | N+1 Profile Page | Written | medium |
| Not started | Priority Job Queue | Written | medium |
| Not started | Retry with Exponential Backoff + Jitter | Written | medium |
| Not started | Running total per accountsqlwindow-functions | Written | medium |
| Not started | Search a rotated sorted arrayarraysbinary-search | Written | medium |
| Not started | Take-home: a rate-limited APIapi-designrate-limitingtake-hometesting | Written | medium |
| Not started | Tell me about a time you broke productionbehavioralfailureownershipstar | Written | medium |
| Not started | Tell me about a time you disagreed with a decisionbehavioralconflictstar | Written | medium |
| Not started | Tell me about the most ambiguous problem you have worked onambiguitybehavioralstar | Written | medium |
| Not started | The Exception Nobody Sees | Written | medium |
| Not started | The loop that should be fast and is notc++cachememoryperformance | Written | medium |
| Not started | The Missing Customers | Written | medium |
| Not started | The Stale Cache | Written | medium |
| Not started | The stale closureclosuresjavascriptreact | Written | medium |
| Not started | Token Bucket Rate Limiter | Written | medium |
| Not started | Users Who Never Logged In | Written | medium |
| Not started | Versioning an API you cannot take downapi-designrestversioning | Written | medium |
| Not started | What does idempotent actually mean?api-designreliabilityrest | Written | medium |
| Not started | When is an atomic not enough?atomicsc++concurrencymutex | Written | medium |
| Not started | Why did my counter get slower with more threads?c++cacheconcurrencyperformance | Written | medium |
| Not started | Design a chat serviceconsistencydistributed-systemshldsystem-design | Written | hard |
| Not started | Design a collaborative document editorconsistencydistributed-systemshldsystem-design | Written | hard |
| Not started | Design a distributed job schedulerdistributed-systemshldreliabilitysystem-design | Written | hard |
| Not started | Design a distributed key-value storeconsistencydistributed-systemshldsystem-design | Written | hard |
| Not started | Design a distributed rate limiterdistributed-systemsrate-limitingsystem-design | Written | hard |
| Not started | Design a file sync serviceconsistencyhldstoragesystem-design | Written | hard |
| Not started | Design a limit order bookdata-structureslldlow-latencytrading | Written | hard |
| Not started | Design a market data distribution systemlock-freelow-latencymarket-datasystem-design | Written | hard |
| Not started | Design a metrics and monitoring systemhldreliabilitystoragesystem-design | Written | hard |
| Not started | Design a news feedcachingdistributed-systemshldsystem-design | Written | hard |
| Not started | Design a payment system and ledgerconsistencyhldreliabilitysystem-design | Written | hard |
| Not started | Design a post and follow-graph serviceconsistencydistributed-systemshldsystem-design | Written | hard |
| Not started | Design a ride-matching servicedistributed-systemshldstoragesystem-design | Written | hard |
| Not started | Design a ticket booking systemconcurrencyconsistencyhldsystem-design | Written | hard |
| Not started | Design a video streaming servicecachinghldqueuessystem-design | Written | hard |
| Not started | Design a web crawlerdistributed-systemshldstoragesystem-design | Written | hard |
| Not started | Design an ad click aggregation pipelineconsistencyhldqueuessystem-design | Written | hard |
| Not started | Design an object storage servicehldreliabilitystoragesystem-design | Written | hard |
| Not started | Fewest machines to finish by a deadlinebinary-searchgreedyoptimisation | Written | hard |
| Not started | Take-home: trade reconciliationcorrectnessdatatake-hometrading | Written | hard |
| Not started | The ABA problematomicsc++concurrencylock-free | Written | hard |
| Not started | Was double-checked locking ever actually broken?c++concurrencymemory-modelsingleton | Written | hard |
| Not started | What does memory_order_relaxed actually guarantee?atomicsc++concurrencymemory-model | Written | hard |
| Not started | What is the hardest technical problem you have solved?behavioralstartechnical-depth | Written | hard |
| Not started | Why is this query slow?indexingperformancequery-planningsql | Written | hard |