What topics should i learn/review going into an internship for zappos?

[Need4Sleep]

In my area Zappos, the famous online shoe company, offers an internship to college students and sharp young high school students(hoping im one of them!) into learning some of the programming business. Not only would this be a great step into learning what coding is like, it also pays very good considering they are already helping you. Now what areas of coding would i need to be fluent in and have knowledge of to have an internship at this company. I know this is a very broad question, i dont expect anyone to even know exactly, im just curious to what branch of c++ i should focus on so i can be accepted this summer. Thanks! Ill try to update this with any new information i can find.