Information Theory is a basic course of information & computing science department I took before. Compared with some mathematics courses, it is a bit easier to a certain degree. But maybe the textbook we used was basic.
Anyway, this course was interesting and seemly useful because we can combine these theories with our real life. This note is the note I took during the final exam period and it may be simple. So if you would like to reference this note, please review it with the use of textbooks.