/java-algorithms-implementation

Algorithms and Data Structures implemented in Java

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Algorithms and Data Structures implemented in Java

This is a collection of algorithms and data structures which I've implement over the years in my academic and professional life. The code isn't overly-optimized but is written to be correct and readable. The algorithms and data structures are well tested and, unless noted, are believe to be 100% correct.

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What's been implemented:

Data Structures

  • AVL Tree
  • B-Tree
  • Binary Heap [backed by an array or a tree]
  • Binary Search Tree
  • Compact Suffix Trie [backed by a Patricia Trie]
  • Disjoint Set
  • Fenwick Tree [Binary Indexed Tree (BIT)]
  • Graph
    • Undirected
    • Directed (Digraph)
  • Hash Array Mapped Trie (HAMT)
  • Hash Map (associative array)
  • Interval Tree
  • Implicit Key Treap
  • KD Tree (k-dimensional tree or k-d tree)
  • List [backed by an array or a linked list]
  • Matrix
  • Patricia Trie
  • Quad-Tree (Point-Region or MX-CIF)
  • Queue [backed by an array or a linked list]
  • Radix Trie (associative array) [backed by a Patricia Trie]
  • Red-Black Tree
  • Segment Tree
  • Skip List
  • Splay Tree
  • Stack [backed by an array or a linked list]
  • Suffix Tree (Ukkonen's algorithm)
  • Suffix Trie [backed by a Trie]
  • Treap
  • Tree Map (associative array) [backed by an AVL Tree]
  • Trie
  • Trie Map (associative array) [backed by a Trie]

Mathematics

  • Distance
    • chebyshev
    • euclidean
  • Division
    • using a loop
    • using recursion
    • using shifts and multiplication
    • using only shifts
    • using logarithm
  • Multiplication
    • using a loop
    • using recursion
    • using only shifts
    • using logarithms
  • Primes
    • is prime
    • prime factorization
    • sieve of eratosthenes

Numbers

  • Integers
    • to binary String
      • using divide and modulus
      • using right shift and modulus
      • using BigDecimal
      • using divide and double
    • is a power of 2
      • using a loop
      • using recursion
      • using logarithm
      • using bits
    • greatest common divisor
      • using Euclid's algorithm
    • to English (e.g. 1 would return "one")
  • Longs
    • to binary String
      • using divide and modulus
      • using right shift and modulus
      • using BigDecimal

Path

  • Find shortest path(s) in a Graph from a starting Vertex
    • Dijkstra's algorithm (non-negative weight graphs)
    • Bellman-Ford algorithm (negative and positive weight graphs)
  • Find minimum spanning tree
    • Prim's (undirected graphs)
  • Find all pairs shortest path
    • Johnsons's algorithm (negative and positive weight graphs)
    • Floyd-Warshall (negative and positive weight graphs)
  • Cycle detection
    • Depth first search while keeping track of visited Verticies
  • Topological sort
  • A* path finding algorithm

Search

  • Get index of value in array
    • Linear
    • Quickselect
    • Binary [sorted array input only]
    • Optimized binary (binary until a threashold then linear) [sorted array input only]
    • Interpolation [sorted array input only]

Sequences

  • Find longest common subsequence (dynamic programming)
  • Find number of times a subsequence occurs in a sequence (dynamic programming)
  • Find i-th element in a Fibonacci sequence
    • using a loop
    • using recursion
    • using matrix multiplication
    • using Binet's formula
  • Find total of all elements in a sequence
    • using a loop
    • using Triangular numbers

Sorts

  • American Flag Sort
  • Bubble Sort
  • Counting Sort (Integers only)
  • Heap Sort
  • Insertion Sort
  • Merge Sort
  • Quick Sort
  • Radix Sort (Integers only)
  • Shell's Sort

String Functions

  • Reverse characters in a string
    • using additional storage (a String or StringBuilder)
    • using in-place swaps
    • using in-place XOR
  • Reverse words in a string
    • using char swaps and additional storage (a StringBuilder)
    • using StringTokenizer and additional (a String)
    • using split() method and additional storage (a StringBuilder and String[])
    • using in-place swaps
  • Is Palindrome
    • using additional storage (a StringBuilder)
    • using in-place symetric element compares
  • Subsets of characters in a String
  • Edit (Levenshtein) Distance of two Strings