Algorithms & Data Structures

A collection of algorithm and data structure implementations in Java, along with code generation helpers for web frameworks. All algorithm methods are annotated with time and space complexity via @InterestingAlgorithm.

Contents

Core Data Structures

Category	Package	Highlights
Linked Lists	linkedlist	Doubly linked list, LRU cache (HashMap + linked list), singly linked list operations (reverse, cycle detection, intersection detection, merge sorted lists)
Trees	trees	BST operations, tree traversals (pre/in/post-order, level-order, iterative + recursive), sorted array/list to BST, trie with prefix search, height/balance checks
Heaps	heap	Max heap (tree-based), min heap (array-based)
Queues	queues	Min priority queue (binary heap-backed), circular buffer
Sets	sets	Disjoint set / union-find with path compression and union by rank
Graphs	graph	Graph, vertex, edge representations

Algorithm Categories

Category	Package	Highlights
Graph Algorithms	graph	BFS, DFS, Dijkstra's shortest path, Bellman-Ford, topological sort, cycle detection, Kruskal's MST, Prim's MST, strongly connected components (Kosaraju's)
Dynamic Programming	dp	0/1 knapsack, unbounded knapsack, coin change (min coins + ways), longest increasing subsequence, edit distance, matrix chain multiplication, rod cutting, longest palindromic substring, Kadane's max subarray, unique paths, min path sum
Backtracking	backtracking	N-queens, generate parentheses, subsets (power set), permutations, combination sum, word search, sudoku solver
Sliding Window	slidingwindow	Max sum subarray of size K, longest substring without repeating chars, minimum window substring, longest substring with K distinct chars, sliding window maximum
Two Pointers	twopointers	Two sum, three sum, container with most water, trapping rain water, remove duplicates in sorted array
Stack Problems	stackproblems	Valid parentheses, evaluate reverse Polish notation, daily temperatures, largest rectangle in histogram, min stack (O(1) getMin)
Binary Search	binarysearch	Search rotated array, find first/last position, search 2D matrix, find peak element, integer sqrt, find min in rotated sorted array
Sorting	sort	Quicksort, mergesort, introsort, heapsort, bubblesort, selection sort, radix sort
Arrays	arrays	Spiral matrix, merge sorted arrays, interval merging, equilibrium indices, permutations, combinations, binary search, two-number sum
Strings	strings	Palindrome detection, longest common substring/subsequence, anagram detection, string reversal, diff
Words	words	Soundex, rhyming detection, syllable splitting, text justification, Roman numeral conversion, N-grams, word frequency
Math	math	Arithmetic expression evaluation, sieve of Eratosthenes, prime factorization, combinatorics (nCk, Catalan, Pascal's triangle), quadratic solver, GCD/LCM, atoi/itoa
Finance	math/finance	Stock profit (single/multiple transactions), peak/valley detection, volatility
Sequences	sequence	Hamming distance, Levenshtein distance, Needleman-Wunsch scoring, Hirschberg alignment
Bit Manipulation	bits	Bitwise operations, bitmap, bitset
Misc	misc	Fibonacci, Excel column conversions, FizzBuzz, climb stairs (DP), Unix path simplification, version comparison, peak element
Graphics	graphics	Image erosion/dilation, Manhattan distance, color averaging, paint fill, convex hull
Games	games	Sudoku generator, Game of Life, Reversi, word square, crossword, Rubik's cube

Code Generation (gen/)

Scaffolding helpers for web frameworks, generating CRUD application boilerplate:

• Rails (gen/rails) - Implemented
• Spring MVC (gen/springmvc) - Partial
• MEAN (gen/mean) - Partial

Language

Java (no build system — compile with javac)

Running Tests

# Compile (excluding alg/io which requires Apache Commons IO)
javac -d build $(find alg test -name "*.java" ! -path "*/io/*" ! -name "WebTest.java" ! -name "WordTest.java")

# Run tests
java -cp build test.alg.misc.MiscUtilsTest
java -cp build test.alg.tree.TreeTest
java -cp build test.alg.sort.SortTest
java -cp build test.alg.math.MathTest
java -cp build test.alg.arrays.ArraysTest