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
1,575 challenges matching your filters
- Code AnalysisIntermediate
Trace: Designated Init
canalysisintermediate - Code AnalysisIntermediate
Trace: Div-Mul Rounding
canalysisintermediate - Code AnalysisIntermediate
Trace: Flexible Array
canalysisintermediate - Code AnalysisIntermediate
Trace: Inline Hint
canalysisintermediate - Code AnalysisIntermediate
Trace: Memcmp
canalysisintermediate - Code AnalysisIntermediate
Trace: Modulo Negative
canalysisintermediate - Code AnalysisIntermediate
Trace: Multi-Dim Array
canalysisintermediate - Code AnalysisIntermediate
Trace: Packed Attribute
canalysisintermediate - Code AnalysisIntermediate
Trace: Pointer to Array
canalysisintermediate - Code AnalysisIntermediate
Trace: Pointer Subtraction
canalysisintermediate - Code AnalysisIntermediate
Trace: Restrict
canalysisintermediate - Code AnalysisIntermediate
Trace: Sequence Point
canalysisintermediate - Code AnalysisIntermediate
Trace: Sizeof Side Effects
canalysisintermediate - Code AnalysisIntermediate
Trace: Sprintf Return
canalysisintermediate - Code AnalysisIntermediate
Trace: Static Function
canalysisintermediate - Code AnalysisIntermediate
Trace: Strchr
canalysisintermediate - Code AnalysisIntermediate
Trace: Strcpy Buffer
canalysisintermediate - Code AnalysisIntermediate
Trace: String Literal Mod
canalysisintermediate - Code AnalysisIntermediate
Trace: Strtok State
canalysisintermediate - Code AnalysisIntermediate
Trace: Struct Reorder
canalysisintermediate - Code AnalysisIntermediate
Trace: Token Pasting
canalysisintermediate - Code AnalysisIntermediate
Trace: VLA Sizeof
canalysisintermediate - Code AnalysisIntermediate
Trace: Void Pointer Arithmetic
canalysisintermediate - Code AnalysisIntermediate
Trace: Volatile
canalysisintermediate - Code AnalysisIntermediate
Trace: XOR Swap — Without Temp
canalysisintermediate - Code AnalysisBeginner
Trace: printf int
canalysisbeginner - Code AnalysisBeginner
Trace: Address of (advanced)
canalysisbeginner - Code AnalysisBeginner
Trace: Dereference — Multi-level
canalysisbeginner - Code AnalysisBeginner
Trace: sizeof
canalysisbeginner - Code AnalysisHard
Array Decay
code-analysisClanguage - Code AnalysisBeginner
Bitwise AND
code-analysisClanguage - Code AnalysisBeginner
Comma Operator
code-analysisClanguage - Code AnalysisHard
Const Cast
code-analysisClanguage - Code AnalysisHard
Dangling Pointer
code-analysisClanguage - Code AnalysisBeginner
Double to Int
code-analysisClanguage - Code AnalysisIntermediate
Macro Expansion Trap
code-analysisClanguage - Code AnalysisHard
Negative Modulo
code-analysisClanguage - Code AnalysisBeginner
Null Pointer Print
code-analysisClanguage - Code AnalysisIntermediate
Post-increment Loop
code-analysisClanguage - Code AnalysisIntermediate
Pointer Arithmetic
code-analysisClanguage - Code AnalysisHard
restrict Pointer
code-analysisClanguage - Code AnalysisHard
Shift Overflow
code-analysisClanguage - Code AnalysisHard
Struct Sizeof
code-analysisClanguage - Code AnalysisIntermediate
String Literal Length
code-analysisClanguage - Code AnalysisHard
Switch Fall-through
code-analysisClanguage - Code AnalysisIntermediate
Ternary Operator
code-analysisClanguage - Code AnalysisHard
Type Promotion
code-analysisClanguage - Code AnalysisHard
Unsigned Underflow
code-analysisClanguage - Code AnalysisHard
XOR Swap Same
code-analysisClanguage - Code AnalysisBeginner
Returning reference to local
cppdanglingreferencescode-analysis - Code AnalysisBeginner
Iterator invalidation in vector loop
cppstlvectoriterator-invalidation - Code AnalysisBeginner
Slicing via by-value base parameter
cppobject-slicingvirtualcode-analysis - Code AnalysisIntermediate
Deleting derived through base pointer
cppvirtualdestructorundefined-behavior - Code AnalysisIntermediate
Capture by reference outliving scope
cpplambdacapturedangling - Code AnalysisIntermediate
Dangling reference in std::async
cppasynclambdacapture - Code AnalysisHard
Dangling string_view from temporary
cppstring_viewdanglingcode-analysis - Code AnalysisHard
Pessimizing std::move on return
cppmove-semanticsrvoanti-pattern - Code AnalysisHard
shared_ptr reference cycle
cppsmart-pointersshared_ptrmemory-leak - Code AnalysisIntermediate
Return local by value
cpprvoreturncode-analysis - Code AnalysisBeginner
Move on const object copies
cppmove-semanticsconst-correctnessgotcha
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.