Thanksgiving code

November 28th, 2008 in Coding, Rants - 1 Comment

I needed a script to loop through the letters of the alphabet and put this in an array: a-z, aa-zz, aaa-zzz, aaaa-zzzz, etc. Through a very rough approach, I’ve satisfied conditions 1-3, but not anything after (source code below).

[syntax,alg.phps,php]

So, all my problems are from the function get_items(). Basically, I don’t want to loop through the $used array to find out what values have a particular length. So based on my analysis, we have a theoretical function f(x, y) which gives the following when run:

f(1, 26) = 0	
f(2, 26) = 26	
f(3, 26) = 702
f(4, 26) = 18278

ie, the set {0, 26, 702, 18278, …}

f(2, 26) - f(1, 26) = 26      = 26 ^ 1
f(3, 26) - f(2, 26) = 676     = 26 ^ 2
f(4, 26) - f(3, 26) = 17576   = 26 ^ 3

Okay, now I see it clearly. Here goes:

[syntax,alg2.phps,php]

So, why do I need this? I have to do a test on an PHP-Ajax newsletter WordPress plugin. On a site I’m working on, we need to send emails to 70000 subscribers, and the current plugin loops through all the records in the database in one go. Of course the max execution time passes before then. I needed to generate a test database of 70000 emails @localhost.com to help me test while I rewrite the plugin.

Well, onto the actual rewrite.

Algorithms for Dummies

November 7th, 2008 in Coding, Rants - 2 Comments

I’m taking my second algorithm class this semester. So far, I think I understand a lot of the algorithms discussed in theory. The problem is translating them to code. Most of the algorithm textbooks I’ve come across are so technical, I haven’t the foggiest idea how to actually go on.

The biggest problem, I think is that I cannot even implement the most basic structure needed — a binary tree — not to talk of directed and undirected graphs. Not knowing doesn’t necessarily translate to not wanting to know, and the fact that I can’t write a simple Insertion-Sort algorithm kind of makes me feel down.

I’m dusting off my old C++ book and starting over again from arrays and linked lists. 🙁

If you happen to know where a poor coder-wannabe can get a simple algorithms book — with code examples — I’d be very grateful.