Honestly I would take a look through a good standard library that provides a lot of algorithms (e.g. C++ or Rust). That has the basics, especially for data structures.
Also have a go at some hacker rank tests. Especially if you want to learn dynamic programming (abysmal name), they absolutely love that.
Yeah IntelliJ does amazingly without type annotations but even it can't do everything. E.g. if you're using libraries without type annotations, or if you don't call functions with every possible type (is your testing that good? No.)
Static types have other benefits anyway so you should use them even if everyone in your team uses IntelliJ.