Tips when porting C++ programs to Rust

So, I've started porting the unrar program to Rust as a project to learn more about both languages, and to practice reading other people's code.

One thing that really surprised me is that there's a lot of code defining basic data structures (like Strings, or vector-like arrays), and I don't know if I should use Rust's built-in ones (or equivalent crates) or reimplement them.

Any tips you could give me?