Hello I am new to competitive programming treat me like a 10th grader. I’ve been doing problem on CF and atcoder I also took part of some of their contest. I felt that I didn’t study it the right way when I looked up online with other people doing their contest and I notice that their code is not similar to me at all and I think they are using the advance tactic and I would love to learn something like that. If you have any book recommendation or any program that worth spending time doing please guide me.
Thank you for time.