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Archive for the ‘algorithms’ Category
Sorting PHP arrays with substrings
In: algorithms| data| php
10 Dec 2009Sorting PHP arrays using usort with substrings
- (4) Comments
- Tags: algorithm
Generating UPC check digit
In: algorithms| php
20 Sep 2009auto generation of upc check digit
- (1) Comment
- Tags: upc
Doubly Linked List in php
In: algorithms
13 Jul 2009linked list in php
- (4) Comments
- Tags: algorithms, linkedlist
Porter Stemming algorithm for search
In: algorithms| php
20 Apr 2009In this post we will see how to use a Stemming algorithm for search purposes.
A stemming algorithm lets you reduce each English input word to its basic root or stem (e.g. ‘walking’ to ‘walk’) so that variations on a word (‘walks’, ‘walked’, ‘walking’) are considered equivalent when searching. This stems can than be used [...]
- (7) Comments
- Tags: language, search
Finding if an array is ordered
In: algorithms
8 Jan 2009I recently wrote a quick code to find if a numeric array is ordered i.e sorted in a ascending or descending order. I needed it to check a sort algorithm I had written. The problem is that the following code has a worst-case running time of O(N). Can we make the running time logarithmic.
- (2) Comments
- Tags: algorithms
Luhn algorithm for validating credit cards
In: algorithms| php
9 Jul 2008The Luhn algorithm also known as the “modulus 10″ or “mod 10″ algorithm, is a checksum formula which can be used to validate credit card numbers. Developed in the 1950’s by IBM scientist Hans Peter Luhn and described in U.S. Patent 2,950,048. A PHP implementation is shown below.
function LuhnCheck($strDigits)
{
$sum = 0;
[...]
- (1) Comment
- Tags: algorithm, php
Linked List implementation in PHP
In: algorithms| php
24 Jun 2008Data structures are one of the core elements of computer science and they are also fun to program. But being a web developer the opportunity for implementing them in any application is quite rare. But then I thought, What the heck! I can just code for the joy of it, and it will also help [...]
- (11) Comments
- Tags: algorithms
