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
- Code AnalysisBeginner
Trace: Array Sum
dsaanalysisarraysbeginner - Code AnalysisIntermediate
Trace: Backtracking
dsaanalysisbacktrackingintermediate - Code AnalysisIntermediate
Trace: BST Search
dsaanalysistreesintermediate - Code AnalysisIntermediate
Trace: DP Table
dsaanalysisdpintermediate - Code AnalysisBeginner
Trace: LOOP #2
dsaanalysisbeginner - Code AnalysisBeginner
Trace: LOOP #3
dsaanalysisbeginner - Code AnalysisBeginner
Trace: LOOP #4
dsaanalysisbeginner - Code AnalysisBeginner
Trace: LOOP #5
dsaanalysisbeginner - Code AnalysisBeginner
Trace: Nested Loops — Triangle
dsaanalysisbig-obeginner - Code AnalysisIntermediate
Trace: Sliding Window
dsaanalysissliding-windowintermediate - Code AnalysisBeginner
Trace: Stack Operations
dsaanalysisstackbeginner - Code AnalysisBeginner
Trace: charAt
dsaanalysisbeginner - Code AnalysisBeginner
Trace: Split
dsaanalysisbeginner - Code AnalysisBeginner
Trace: STR #1
dsaanalysisbeginner - Code AnalysisBeginner
Trace: STR #2
dsaanalysisbeginner - Code AnalysisBeginner
Trace: STR #3
dsaanalysisbeginner - Code AnalysisBeginner
Trace: STR #4
dsaanalysisbeginner - Code AnalysisBeginner
Trace: STR #5
dsaanalysisbeginner - Code AnalysisBeginner
Trace: toUpperCase
dsaanalysisbeginner - Code AnalysisBeginner
Trace: String Reverse
dsaanalysisstringsbeginner - Code AnalysisIntermediate
Trace: Two Pointers
dsaanalysistwo-pointersintermediate - Multiple ChoiceBeginner
Arrays: Access Time
dsaarraysbeginner - Multiple ChoiceBeginner
Arrays: Definition
dsaarraysbeginner - Multiple ChoiceBeginner
Arrays: Deletion
dsaarraysbeginner - Multiple ChoiceBeginner
Fixed vs Dynamic Arrays
dsaarraysbeginner - Multiple ChoiceBeginner
Arrays: Indexing
dsaarraysbeginner - Multiple ChoiceBeginner
Arrays: Insert at End
dsaarraysbeginner - Multiple ChoiceBeginner
Arrays: Insert in Middle
dsaarraysbeginner - Multiple ChoiceBeginner
Arrays: Memory Layout
dsaarraysbeginner - Multiple ChoiceBeginner
Arrays vs Linked Lists
dsaarraysbeginner - Multiple ChoiceIntermediate
Backtracking: Definition
dsabacktrackingintermediate - Multiple ChoiceIntermediate
Backtracking: N-Queens
dsabacktrackingintermediate - Multiple ChoiceIntermediate
Backtracking: Permutations
dsabacktrackingintermediate - Multiple ChoiceIntermediate
Backtracking: Pruning
dsabacktrackingintermediate - 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 ChoiceIntermediate
Merge Sort
dsadivide-conquerintermediate - Multiple ChoiceIntermediate
Quick Sort
dsadivide-conquerintermediate - Multiple ChoiceIntermediate
DP: Definition
dsadpintermediate - Multiple ChoiceHard
Edit Distance (Levenshtein)
dsadphard - Multiple ChoiceIntermediate
DP: Fibonacci Optimization
dsadpintermediate - Multiple ChoiceHard
0/1 Knapsack
dsadphard - Multiple ChoiceHard
Longest Common Subsequence
dsadphard - Multiple ChoiceIntermediate
Memoization
dsadpintermediate - Multiple ChoiceHard
Subset Sum
dsadphard - Multiple ChoiceIntermediate
Tabulation
dsadpintermediate - Multiple ChoiceIntermediate
DP vs Greedy
dsadpintermediate - Multiple ChoiceHard
DP vs Naive Recursion
dsadphard - Multiple ChoiceHard
Fenwick Tree (BIT)
dsafenwick-treehard - Multiple ChoiceHard
Fenwick vs Segment Tree
dsafenwick-treehard - Multiple ChoiceIntermediate
Adjacency List
dsagraphsintermediate - Multiple ChoiceHard
Bellman-Ford Algorithm
dsagraphshard - Multiple ChoiceIntermediate
Breadth-First Search (BFS)
dsagraphsintermediate - Multiple ChoiceIntermediate
BFS: Use Cases
dsagraphsintermediate - Multiple ChoiceIntermediate
Graph: Definition
dsagraphsintermediate - Multiple ChoiceIntermediate
Depth-First Search (DFS)
dsagraphsintermediate - Multiple ChoiceIntermediate
DFS: Use Cases
dsagraphsintermediate - Multiple ChoiceHard
Dijkstra's Algorithm
dsagraphshard
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