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.
Filter by type
Filter by difficulty
Popular topics
6 challenges matching your filters
Clear topic filter- Multiple ChoiceHard
Sharding key choice
system-designdatabasessharding - Multiple ChoiceIntermediate
Hot partition in Kafka
system-designmessagingkafkasharding - Multiple ChoiceBeginner
Hash sharding hotspot risk
shardinghashinghotspots - Multiple ChoiceHard
Sharded Timers for Job Scheduler
schedulershardingtimers - Multiple ChoiceBeginner
Sharded counters for real-time leaderboard
leaderboardshardingcounters - Code AnalysisHard
Hot shard from a skewed key
system-designshardinghot-partition
Practice now, dominate the arena
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.