Data Structures & Algorithms Tutorials

Patterns for coding interviews with step-by-step animations. Every lesson is free, visual and written in simple English.

In-depth visual guides

Data Structures & AlgorithmsBinary Search

Step through binary search on a live array, see why O(log n) is so fast, then learn the iterative and recursive code, lower bound, first and last occurrence, binary search on the answer, common bugs and interview questions.

12 min read2 interactive visualsBeginner

Foundations & Array Patterns

Big-O & ComplexityBeginner · 16 min Arrays, Hashing & Prefix SumsBeginner · 15 min Two PointersBeginner · 15 min Sliding WindowBeginner · 15 min Binary SearchBeginner · 16 min Sorting AlgorithmsBeginner · 16 min

Linear Data Structures

Stacks, Queues & Monotonic StacksBeginner · 13 min Linked ListsBeginner · 14 min Heaps & Priority QueuesIntermediate · 14 min

Trees & Graphs

Trees & Graphs, VisuallyBeginner · 20 min Binary Trees & BSTsIntermediate · 14 min Graphs: BFS & DFSIntermediate · 15 min Topological Sort, Dijkstra & Union-FindAdvanced · 18 min

Recursion & Dynamic Programming

Recursion & BacktrackingIntermediate · 14 min Dynamic Programming (1-D)Intermediate · 15 min Dynamic Programming (2-D)Advanced · 15 min

Greedy & Bits

Greedy & IntervalsIntermediate · 14 min Bit ManipulationBeginner · 15 min