Collections API can do all that and a lot more.
I wonder why teachers choose Java as a language for teaching and then expect their students to do things in it that the core API can do very well thank you.

I know the curiculum is left over from C, but it's better done in C anyway. Beautiful language, perfect for teaching core programming skills (apart from OO).

And no, we're not going to do your homework for you. If you have SPECIFIC questions about something where you're stuck on a detail we may be able to steer you in the right direction but we're not going to write your entire paper (which is what you're essentially asking).