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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5,893 challenges total
- Multiple ChoiceBeginner
ROLLBACK
backendbeginner - Multiple ChoiceHard
Isolation Levels
backendhard - Multiple ChoiceIntermediate
Connection Pooling
backendintermediate - Multiple ChoiceIntermediate
N+1 Problem
backendintermediate - Multiple ChoiceIntermediate
Eager vs Lazy Loading
backendintermediate - Multiple ChoiceIntermediate
ORM Purpose
backendintermediate - Multiple ChoiceIntermediate
Prepared Statements
backendintermediate - Multiple ChoiceBeginner
Aggregate Functions
backendbeginner - Multiple ChoiceIntermediate
UNION vs UNION ALL
backendintermediate - Multiple ChoiceIntermediate
EXPLAIN
backendintermediate - Multiple ChoiceIntermediate
Views
backendintermediate - Multiple ChoiceIntermediate
Stored Procedures
backendintermediate - Multiple ChoiceIntermediate
Database Migrations
backendintermediate - Code AnalysisIntermediate
SELECT with JOIN
backendintermediate - Code AnalysisIntermediate
GROUP BY count
backendintermediate - Code AnalysisIntermediate
LEFT JOIN vs INNER
backendintermediate - Code AnalysisIntermediate
Transaction flow
backendintermediate - Code AnalysisIntermediate
Index choice
backendintermediate - Code AnalysisHard
Normalization 2NF
backendhard - Code AnalysisIntermediate
EXPLAIN output
backendintermediate - Code AnalysisIntermediate
Connection pool
backendintermediate - Code AnalysisIntermediate
SQL injection vulnerable
backendintermediate - Code AnalysisIntermediate
Prepared statement
backendintermediate - Code AnalysisIntermediate
NULL handling
backendintermediate - Code AnalysisBeginner
DISTINCT clause
backendbeginner - Multiple ChoiceIntermediate
CI/CD Pipeline
backendintermediate - Multiple ChoiceIntermediate
Docker Container
backendintermediate - Multiple ChoiceIntermediate
Docker vs VM
backendintermediate - Multiple ChoiceIntermediate
Dockerfile
backendintermediate - Multiple ChoiceIntermediate
Docker Compose
backendintermediate - Multiple ChoiceIntermediate
Kubernetes
backendintermediate - Multiple ChoiceIntermediate
K8s Pod
backendintermediate - Multiple ChoiceIntermediate
K8s Service
backendintermediate - Multiple ChoiceIntermediate
Infrastructure as Code
backendintermediate - Multiple ChoiceHard
GitOps
backendhard - Multiple ChoiceIntermediate
Monitoring Tools
backendintermediate - Multiple ChoiceIntermediate
Rollback Strategy
backendintermediate - Multiple ChoiceHard
Immutable Infrastructure
backendhard - Multiple ChoiceIntermediate
Environment Variables
backendintermediate - Multiple ChoiceIntermediate
Log Aggregation
backendintermediate - Multiple ChoiceIntermediate
Secrets Management
backendintermediate - Multiple ChoiceIntermediate
Horizontal Pod Autoscaling
backendintermediate - Multiple ChoiceHard
Liveness vs Readiness
backendhard - Multiple ChoiceIntermediate
Helm Charts
backendintermediate - Multiple ChoiceHard
ArgoCD
backendhard - Multiple ChoiceIntermediate
Downtime Minimization
backendintermediate - Code AnalysisIntermediate
Dockerfile instructions
backendintermediate - Code AnalysisIntermediate
K8s Deployment YAML
backendintermediate - Code AnalysisIntermediate
CI pipeline steps
backendintermediate - Code AnalysisIntermediate
Rolling update
backendintermediate - Code AnalysisIntermediate
Environment config
backendintermediate - Code AnalysisIntermediate
Prometheus metric
backendintermediate - Code AnalysisIntermediate
Secrets in K8s
backendintermediate - Code AnalysisIntermediate
HPA configuration
backendintermediate - Code AnalysisHard
Readiness probe
backendhard - Multiple ChoiceIntermediate
Repository Pattern
backendintermediate - Multiple ChoiceIntermediate
Service Layer
backendintermediate - Multiple ChoiceIntermediate
Dependency Injection
backendintermediate - Multiple ChoiceIntermediate
Factory Pattern
backendintermediate - Multiple ChoiceIntermediate
Observer Pattern
backendintermediate
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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.