Statistics and probability don't directly relate to anything in TADM from what I can recall. There's not much to the maths beyond high school stuff. Some discrete maths will help though. Graphs theory, trees and functions especially. Schaum's Outline of Discrete Mathematics is decent.

Obviously Skiena's book is in C- so be somewhat familiar with it. Again no need to go crazy deep into C before you start. You can learn as you go.

I'd recommend just diving in and using other resources as references if you come across anything you don't know, rather than spending too much time working though "pre-requisites".