Hello guys. :)

I'm from Palestine, and I'm new in the field of competitive programming, actually the whole country is new in this field, we have no national IOI yet, and it's just the second year where a there was a national ACM ICPC contest.

so I wonder what is the best thing to do to get started (and fast as I really hope that next year we get a good rank in the regional ICPC), should I read a specific book? I started participating in CF's contests and topcoders ones, and I found that I can solve Div2 easy problems pretty fast, but when it comes to C,D and E ones, which usually need algorithms I kinda stuck in there, so is there a source where I can learn them well?

thanks in advance :)