For exploring competitive coding beyond what we've covered here in this short timeframe, here are some additional resources that will help you a lot:
- Competitive Programmer’s Handbook - one of the best and most concise books to start out with
- CP-Algorithms - a great website covering most well-known algorithms
- Principles of Algorithmic Problem Solving - longer and more detailed book, covers some more algorithms in greater depth, best used as a reference
- Codeforces EDU has a few courses on specific topics while Codeforces Catalog is a good place to look for blogs explaining a certain topic.
Another great website is USACO Guide, which has structured topic-wise explanations along with example problems and links to further resources. This structured path might take time but will definitely pay off in the long run.
Here are the major platforms that hold regular CC competitions: