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
238 challenges matching your filters
Clear topic filter- Multiple ChoiceBeginner
Go: Struct embedding
gomcqbeginner - Multiple ChoiceBeginner
Go: json struct tag
gomcqbeginner - Multiple ChoiceBeginner
Go: iota keyword
gomcqbeginner - Multiple ChoiceBeginner
Go: Variadic params
gomcqbeginner - Multiple ChoiceBeginner
Go: Named return values
gomcqbeginner - Multiple ChoiceBeginner
Go: Closure captures
gomcqbeginner - Multiple ChoiceBeginner
Go: nil map write
gomcqbeginner - Multiple ChoiceBeginner
Go: nil slice append
gomcqbeginner - Multiple ChoiceBeginner
Go: GOPATH purpose
gomcqbeginner - Multiple ChoiceBeginner
Go: go.mod defines
gomcqbeginner - Multiple ChoiceBeginner
Go: go.sum purpose
gomcqbeginner - Multiple ChoiceBeginner
Go: Race detector flag
gomcqbeginner - Multiple ChoiceBeginner
Go: Benchmark signature
gomcqbeginner - Multiple ChoiceBeginner
Go: Table-driven tests
gomcqbeginner - Multiple ChoiceBeginner
Go: HTTP server start
gomcqbeginner - Multiple ChoiceBeginner
Go: JSON decode func
gomcqbeginner - Multiple ChoiceBeginner
Go: time.Now() returns
gomcqbeginner - Multiple ChoiceBeginner
Go: os.Args[0] value
gomcqbeginner - Multiple ChoiceBeginner
Go: sync.Once count
gomcqbeginner - Multiple ChoiceBeginner
Go: atomic.AddInt64
gomcqbeginner - Multiple ChoiceBeginner
Go: GOMAXPROCS sets
gomcqbeginner - Multiple ChoiceBeginner
Go: GC triggers when
gomcqbeginner - Multiple ChoiceBeginner
Go: unsafe.Pointer use
gomcqbeginner - Multiple ChoiceBeginner
Go: reflect.TypeOf
gomcqbeginner - Multiple ChoiceBeginner
Go: Build tags //go:build
gomcqbeginner - Multiple ChoiceBeginner
Go: cgo purpose
gomcqbeginner - Multiple ChoiceBeginner
Go: Module path is
gomcqbeginner - Multiple ChoiceBeginner
Go: go mod vendor
gomcqbeginner - Multiple ChoiceHard
Context Cancellation
gomcqhard - Multiple ChoiceBeginner
defer Order
gomcqbeginner - Multiple ChoiceHard
Goroutine Leaks
gomcqhard - Multiple ChoiceHard
Typed Nil Interface
gomcqhard - Multiple ChoiceIntermediate
Nil Map Write
gomcqintermediate - Multiple ChoiceIntermediate
Race Detector
gomcqintermediate - Multiple ChoiceIntermediate
select default
gomcqintermediate - Multiple ChoiceIntermediate
Slice Capacity
gomcqintermediate - Multiple ChoiceIntermediate
strings.Builder
gomcqintermediate - Multiple ChoiceIntermediate
Value vs Pointer Receiver
gomcqintermediate - Multiple ChoiceIntermediate
async Function Return
javascriptmcqintermediate - Multiple ChoiceHard
Event Loop Order
javascriptmcqhard - Multiple ChoiceBeginner
NaN Type
javascriptmcqbeginner - Multiple ChoiceBeginner
null vs undefined
javascriptmcqbeginner - Multiple ChoiceIntermediate
Optional Chaining
javascriptmcqintermediate - Multiple ChoiceIntermediate
Prototype Lookup
javascriptmcqintermediate - Multiple ChoiceBeginner
Object Spread
javascriptmcqbeginner - Multiple ChoiceHard
Temporal Dead Zone
javascriptmcqhard - Multiple ChoiceIntermediate
this in Arrow Functions
javascriptmcqintermediate - Multiple ChoiceIntermediate
var Hoisting
javascriptmcqintermediate - Multiple ChoiceIntermediate
Star Unpacking
pythonmcqintermediate - Multiple ChoiceIntermediate
Context Managers
pythonmcqintermediate - Multiple ChoiceHard
Descriptors
pythonmcqhard - Multiple ChoiceIntermediate
Dict Ordering
pythonmcqintermediate - Multiple ChoiceIntermediate
Generators
pythonmcqintermediate - Multiple ChoiceHard
Python: The GIL
pythonmcqhard - Multiple ChoiceBeginner
is vs ==
pythonmcqbeginner - Multiple ChoiceHard
Name Resolution: LEGB
pythonmcqhard - Multiple ChoiceIntermediate
Mutable Default Argument
pythonmcqintermediate - Multiple ChoiceIntermediate
Copy Semantics
pythonmcqintermediate
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.