Gist of the Day: Find All Paths for an Undirected Graph

I’ve been doing a lot of stuff lately with data structures and algorithms. This is one that seemed remarkably complicated to me – and still kinda does – when I started. It’s not as trivial as a binary tree mainly because there are far fewer rules. There’s a whole lot of stuff you can do with graphs, and this is by no means an advanced or complicated usage of them. This is as simple a task you can do with a graph.
The task at hand is to find all possible paths between two vertices. Continue reading “Gist of the Day: Find All Paths for an Undirected Graph”

Gist of the Day: Find Which List Items Make Up a Given Sum

Here’s the scenario: you have two lists of integers, and you have a sum. Write an algorithm – in Perl, of course – to find which two items when summed give you a specified number. If no pairing exists, don’t return anything. If a pairing does exist, return the first pair you encounter. Remember, you could get two very large input lists. Continue reading “Gist of the Day: Find Which List Items Make Up a Given Sum”

Bonus Post: Links About Process Control in GNU/Linux!

So, I’ve been looking into how process control works in GNU/Linux environments, and I thought I’d share some stuff with you guys since you totally care.

That’s all I have for now. Please use the comments section if you’d like to suggest additional articles.

Gist of the Day: Re-Inventing Hashes… In Perl.

Before you begin the well-deserved flaming, please understand that I do not intend on submitting this to CPAN. This is purely an academic exercise to demonstrate the algorithm (poorly), and to help me practice some stuff. I understand that this isn’t terribly efficient, and I am quite confident that one could do this much faster (and probably has many times over). I wrote this for fun, and for boredom, and I’m posting it because I thought it was cool and because I promised you I’d post stuff.
This algorithm is pretty simple. The premise is that you take a key value of some sort, you hash it using any algorithm, and then you take the mod of that hash value by the capacity of your hash table, and that gives you an index! It’s pretty simple, and even in the implementation I have here I believe it’s not a terrible look-up time.
The basic idea is this: $array_index = hashval($key) % $array_capacity
Continue reading “Gist of the Day: Re-Inventing Hashes… In Perl.”

Gist of the Day: Process Control with fork(), exec(), and kill()

I feel really bad for leaving you all high and dry yesterday… really bad… okay, you’re right, I don’t really feel all that bad.
I have a doosey for you all today though, no doubt about it! One of the most common trends in computers these days is multi-processing. Multiple cores means one program can do more work by spawning extra threads or child processes. I’ve already done a bit of stuff with threading, so here’s a bunch of stuff with forking (tee-hee). Continue reading “Gist of the Day: Process Control with fork(), exec(), and kill()”