DS & Algorithms Primer

Data Structures & Algorithms Primer

125+ algorithms. Step-through visualizations. Kotlin code. Learn by seeing.

Explore Topics Try the Visualizer

Interactive Algorithm Visualizer

Step through algorithms with your own data. Watch arrays, trees, graphs, and stacks update in real time.

Divide, sort, and merge with step-by-step animation

Dijkstra's Algorithm

Shortest path with priority queue visualization

Watch the search space halve at each step

Backtracking with board state visualization

Tree Traversals

BFS and DFS traversals on binary trees

Watch the DP table fill cell by cell

See all 125+ visualizations →

Data Structures

Memory model, Kotlin array types, core operations, sorting algorithms, and 15 algorithm patterns with visual diagrams, complexity tags, and hover explanations.

IntArray MutableList 2D Matrix 10 Sorts

Immutability & memory, string pool, creation & comparison, transformation, splitting & joining, StringBuilder, regex, character arithmetic, and KMP/Rabin-Karp string matching.

String StringBuilder Regex KMP

HashMap concepts, hashing internals, collision resolution, Kotlin map types, core operations, sorted maps, frequency counting, two-sum, sliding window, caching, and LRU cache.

HashMap LinkedHashMap TreeMap LRU Cache

Set concepts, Kotlin set types, creation & mutation, set algebra (union, intersect, difference), sorted sets, duplicate detection, consecutive sequence, and first unique element.

HashSet LinkedHashSet TreeSet Set Algebra

Singly & doubly linked lists, sentinel nodes, fast/slow pointers, reversal, cycle detection, merge sorted lists, partition, rotate, k-group reverse, and LRU cache.

ListNode DoublyLinked Floyd's 19 Algos

LIFO fundamentals, ArrayDeque, monotonic stacks, bracket matching, expression evaluation, histogram, rain water, DFS, tree traversals, and 19 algorithm patterns.

ArrayDeque Monotonic LIFO 19 Algos

FIFO fundamentals, deques, priority queues (heaps), BFS, level-order traversal, monotonic deque, Dijkstra's, sliding window max/min, two-heap median, and 20 algorithm patterns.

ArrayDeque PriorityQueue BFS 20 Algos

Binary trees, BST operations & validation, AVL & Red-Black trees, all traversals, tries, segment trees, Fenwick trees, and 24 algorithm patterns.

BST Trie Traversals 24 Algos

Graph representations, BFS/DFS traversals, shortest paths (Dijkstra, Bellman-Ford, Floyd-Warshall), MSTs (Kruskal, Prim), Union-Find, topological sort, and 35 algorithm patterns.

Adjacency List Dijkstra Union-Find 35 Algos

Algorithmic Techniques

Dynamic Programming

Memoization vs tabulation, 1D & 2D DP, knapsack, LCS, edit distance, interval DP, bitmask DP, state machine patterns, and 30+ algorithm patterns.

Knapsack LCS State Machine 30+ Algos

Recursion & Backtracking

Call stack, tail recursion, divide-and-conquer, memoization, backtracking templates, subsets, permutations, combinations, N-Queens, Sudoku, and 20+ patterns.

Backtracking D&C Memoization 20+ Algos

Fundamentals

Big O & Complexity

Asymptotic notation, all complexity classes from O(1) to O(n!), analyzing loops & recursion, Master Theorem, amortized analysis, practical limits, and Kotlin/JVM library complexities.

Big O Master Theorem Amortized 30 Sections