lol

I think that the code is just used to "Seed" the random number generator.
The way computers create random numbers is by starting out with one number, and then apply a complex function to that to get the next number. So if you start with the same seed, you will get the same sequence of "random" numbers, and thus the same map. Usually you seed on the system microsecond timer, but they want maps to be reproducable, so they choose this way of a seed string.

I think that's what splode was talking about with the Hash or Algorithm. They work pretty much how u just described.

what he explained is just how they make a number from a string. However I do not think they use a cryptographic hash(like md5) because of the legal export restrictions on that. It's probably something simple, like, take the ascii value of every character and multiply those, modulo some prime.

What he didn't explain is how this single number can create an entire reproducable random map

They most likely have a basic map template, like a set of possible spawn points, and offset some positions etc by using a cut normal distribution. That's how I would do it to make sure the map is consistent and "possible".