Hi everyone, I recently discovered about competetive programming and since then i m spending all my time just watching videos or reading about algorithms. i found the basic algorithms very simple to understand and implement but I am having a hard time with understanding implementations of bfs, dfs and other similar topics. Maybe its because of my unfamiliarity with STL. I also recently discovered about IOI , I solved all the recent ZIO papers.I need some help regarding the use of basic stls like vector, maps etc and implementations of intermediate algorithms(with explanations). Also should i switch to java and is there any way to implement these algorithms without using stl?.Can i use a adjancency matrix instead of a list?

P.S- I plan to be able to start solving codeforces graph problems by 3 july .I am currently in 9th grade and really want to make it to the IOI.

Thanks in advance:)