Learn Data Structure and Algorithms by PHP

You need to have basic understanding of the PHP programming language to proceed with the codes from this repository.

Introduction to PHP
Data Structure
- Linked List
- Stack
- Queue
- Binary Search Tree (BST)
- Heap
- Hash Table
- Disjoint Set Union (Union Find)
- Trie
- Suffix Array
- Segment Tree
- Binary Indexed Tree (BIT)
- Heavy Light Decomposition
Searching
Sorting
- Selection Sort
- Bubble Sort
- Insertion Sort
- Merge Sort
- Quick Sort
- Bucket Sort
- Counting Sort
- Heap Sort
- Radix Sort
Graph Algorithms
- Graph Representation
- Breadth First Search (BFS)
- Depth First Search (DFS)
- Topological Sort
- Strongly Connected Components (SCC)
- Minimum Spanning Tree (MST)
- All Pairs Shortest Path (Floyd Warshall's Algorithm)
- Single Source Shortest Path Algorithm
  - Djkastra's Algorithm
  - Bellman Ford Algorithm
- Directed Acyclic Graph
- Bipartite Matching
- Articulation Point, Bridge
- Euler Tour/Path
- Hamiltonian Cycle
- Stable Marriage Problem
- Chinese Postman Problem
- 2-satisfiability
- Flow Algorithms
  - Maximum Flow
  - Minimum Cut
  - Min-Cost Max Flow
  - Maximum Bipartite Matching
  - Vertex Cover
Dynamic Programming
- Rod Cutting
- Maximum Sum (1D, 2D)
- Coin Change
- Longest Common Subsequence
- Longest Increasing Subsequence
- Matrix Multiplication
- Edit Distance (Levenshtein distance)
- 0/1 Knapsack
- Travelling Salesman Problem
- Optimal Binary Search Tree
Greedy Algorithms
- Activity Selection/Task Scheduling
- Huffman Coding
- Knapsack Problem (Fractional Knapsack)
String Algorithms
- Rabin-Karp Algorithm
- Knuth-Morris-Pratt Algorithm
- Z Algorithm
- Aho-Korasick Algorithm
- Manachers Algorithm
- Boyr-Moore Algorithm
Number Theory
- Greatest Common Divisor (GCD)
- Longest Common Multiplier (LCM)
- Euler Totient (Phi)
- Prime finding(Sieve of Eratosthenes)
- Prime factorization
- Factorial
- Fibonacci
- Counting, Permutation, combination
- Exponentiation
- Big Mod
- Euclid, Extended euclid
- Josephus Problem
- Farey Sequence
- Catalan numbers
- Burnside's lemma/circular permutation
- Modular inverse
- Probability
- Chinese Remainder Theorem
- Gaussian Elmination method
- Dilworth's Theorem
- Matrix Exponentiation
Computational Geometry
- Pick's Theorem
- Convex hull
- Line Intersection
- Point in a polygon
- Area of a polygon
- Line Sweeping
- Polygon intersection
- Closest Pair
Game Theory
- Take Away Game
- Nim's Game
- Sprague-grundy Number
Others
- BackTracking
  - N-Queen's Problem

Introduction

PHP is a dynamic language with Weak Typing. That means you don't have to declare the type of a variable ahead of time. The type will get determined automatically while the program is being processed. That also means that variables are not "bound" to a specific data type.:

$foo = "x";    // foo contains a string
$foo = $foo + 2; // foo concatenates with a number
echo $foo;

Data Types in PHP

PHP supports the following data types:

Four scalar types:
- boolean (True and False)
- integer (Positive and negative numbers)
- float (Floating point numbers)
- string (series of characters)
Four compound types:
- array
- object
- callable
- iterable
Two special types
- NULL
- resource

More details about data types in PHP:

Object Oriented Programming in PHP

Big-O Notation and Time Complexity Analysis

Algorithms in plain English: time complexity and Big-O notation

Big-O Cheat Sheet Link

How to Use

If you have PHP installed in your machine you can easily run a PHP file using:

php file_name.php

If php command not working in your terminal/command line, then you might need to add it to your environment Path.

Algorithm-archive/Learn-Data_Structure-Algorithm-by-PHP

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