had the same problem when i lived in the dorms one yr. here's how to take care of it the right way:

1) clean ur place up, like really
2) make sure anything that contains any sort of food is SEALED
3) set up multiple ant traps, little black things where they go in, get some shit and carry it back to where they come from
4) sit back and wait, ur problem should be taken care of in about a week