If I decide to learn an algorithm or a data structure with which I am not familiar yet, and decide to read some blog or an article about that algorithm or data structure or watch some video tutorials, and solve some problems (like 4-5 problems) (which are usually provided in the blog) related to it, can I now conclude that I have learned that algorithm or data structure? Can I now expect myself to solve any problem related to it, if it comes in any contest?

What are your views about using the book Guide to Competitive Programming: Learning and Improving Algorithms Through Contests (pdf — book) as a refence book while preparing for International Olympiad in Informatics (IOI).

If you know some other good books, please recommend in the comments.

Thank you.