Challenge Library
Coding Challenges
5,893 curated questions across every arena — browse by topic, then jump into a live 3-minute battle to put them to the test.
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9 challenges matching your filters
Clear topic filter- Multiple ChoiceHard
Cache stampede / thundering herd
system-designcachingstampede - Multiple ChoiceHard
Probabilistic early expiration
system-designcachingstampede - Multiple ChoiceHard
Cache invalidation on write
system-designcachingcache-invalidation - Multiple ChoiceHard
URL Shortener Hot Key Mitigation
url-shortenerhot-keycaching - Code AnalysisHard
Cache stampede on expiry
system-designcachingstampede - Code AnalysisHard
Thundering herd with negative result
system-designcachingcache-penetration - Code AnalysisHard
Bloom filter with no eviction
system-designcachingbloom-filter - Multiple ChoiceHard
Thundering herd on cache expiry
architectureresiliencecaching - Code AnalysisHard
Thundering herd on expiry
architectureresiliencecaching
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Every challenge here is drawn from the live Code Royale pool. Review a question, then head to the arena to answer under pressure against a real opponent — 3-minute matches, Elo ranking, and badge tiers on the line.