Practicing problems can give you a better familiarity with algorithms so you can ace your next interview. There are many sites out there but HackerRank and LeetCode are some of the more popular ones. In addition, doing these problems don't have to just be to practice interviews.
Here are some general resources that you can take advantage of from most classes
Lecture Notes / Textbook (if available)
Office Hours
CS Mentors
Class Forum
Labs and Discussion
If you find yourself struggling, make sure that you try to seek out these resources and don’t be shy. You aren’t here to sit in class and stare at a screen but rather to learn the content. If you need help, seek it out and you’ll thank yourself later.
Looking over past exams and practicing is a great way to prepare for tests and to study class material. They’re actual problems and there is a large collection so you can practice all you want.
Many classes will offer a mock exam as well as links to past exams.