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
169 challenges matching your filters
Clear topic filter- Multiple ChoiceBeginner
Arrays: Insert in Middle
dsaarraysbeginner - Multiple ChoiceBeginner
Arrays: Memory Layout
dsaarraysbeginner - Multiple ChoiceBeginner
Arrays vs Linked Lists
dsaarraysbeginner - Multiple ChoiceBeginner
Big-O: Definition
dsabig-obeginner - Multiple ChoiceBeginner
O(1) — Constant Time
dsabig-obeginner - Multiple ChoiceBeginner
O(n) — Linear Time
dsabig-obeginner - Multiple ChoiceBeginner
O(n²) — Quadratic Time
dsabig-obeginner - Multiple ChoiceBeginner
Hash Table: Collision
dsahash-tablebeginner - Multiple ChoiceBeginner
Hash Table: Definition
dsahash-tablebeginner - Multiple ChoiceBeginner
Hash Table: Lookup
dsahash-tablebeginner - Multiple ChoiceBeginner
Hash Table vs Array
dsahash-tablebeginner - Multiple ChoiceBeginner
Linked List: Definition
dsalinked-listbeginner - Multiple ChoiceBeginner
Head and Tail
dsalinked-listbeginner - Multiple ChoiceBeginner
Singly vs Doubly Linked List
dsalinked-listbeginner - Multiple ChoiceBeginner
Linked List: Node Visiting
dsalinked-listbeginner - Multiple ChoiceBeginner
LL vs Array: Access
dsalinked-listbeginner - Multiple ChoiceBeginner
LL vs Array: Insert at Head
dsalinked-listbeginner - Multiple ChoiceBeginner
Big-O: Logarithmic
dsamcqbeginner - Multiple ChoiceBeginner
Heap Property
dsamcqbeginner - Multiple ChoiceBeginner
Two Pointers
dsamcqbeginner - Multiple ChoiceBeginner
Variable Swap
dsabeginner - Multiple ChoiceBeginner
Array Initialization
dsabeginner - Multiple ChoiceBeginner
Loop Types
dsabeginner - Multiple ChoiceBeginner
Conditional Short Circuit
dsabeginner - Multiple ChoiceBeginner
Default Parameters
dsabeginner - Multiple ChoiceBeginner
Object Keys
dsabeginner - Multiple ChoiceBeginner
Map vs Object
dsabeginner - Multiple ChoiceBeginner
Set Uniqueness
dsabeginner - Multiple ChoiceBeginner
Array Destructuring
dsabeginner - Multiple ChoiceBeginner
Spread Operator
dsabeginner - Multiple ChoiceBeginner
What is a variable?
dsabeginner - Multiple ChoiceBeginner
What is a loop?
dsabeginner - Multiple ChoiceBeginner
What is a function?
dsabeginner - Multiple ChoiceBeginner
What does if/else do?
dsabeginner - Multiple ChoiceBeginner
What is a boolean?
dsabeginner - Multiple ChoiceBeginner
What is parseInt?
dsabeginner - Multiple ChoiceBeginner
What does Math.floor do?
dsabeginner - Multiple ChoiceBeginner
What is NaN?
dsabeginner - Multiple ChoiceBeginner
What is null?
dsabeginner - Multiple ChoiceBeginner
What does typeof do?
dsabeginner - Multiple ChoiceBeginner
What is a char?
dsabeginner - Multiple ChoiceBeginner
What is a delimiter?
dsabeginner - Multiple ChoiceBeginner
What is whitespace?
dsabeginner - Multiple ChoiceBeginner
What is a comment?
dsabeginner - Multiple ChoiceBeginner
What is a syntax error?
dsabeginner - Multiple ChoiceBeginner
What is a runtime error?
dsabeginner - Multiple ChoiceBeginner
What is a logical error?
dsabeginner - Multiple ChoiceBeginner
What is pseudocode?
dsabeginner - Multiple ChoiceBeginner
What is an algorithm?
dsabeginner - Multiple ChoiceBeginner
What is a flowchart?
dsabeginner - Multiple ChoiceBeginner
What is stdin?
dsabeginner - Multiple ChoiceBeginner
What is stdout?
dsabeginner - Multiple ChoiceBeginner
What is stderr?
dsabeginner - Multiple ChoiceBeginner
What is a constant?
dsabeginner - Multiple ChoiceBeginner
What is a parameter?
dsabeginner - Multiple ChoiceBeginner
What is a return value?
dsabeginner - Multiple ChoiceBeginner
What is scope?
dsabeginner - Multiple ChoiceBeginner
What is hoisting?
dsabeginner - Multiple ChoiceBeginner
What is a callback?
dsabeginner - Multiple ChoiceBeginner
What is closure?
dsabeginner
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.