Do people still write their own data structures and algorithms?

Instead of the STL and similar libraries in other languages?

As a newbie, how much should I delve into this part of software development? Breadth first or depth?

Using the STL with Android NDK C++

I am trying to use the STL in an Android NDK C++ File. I try to use map, vector and various other stl classes and I cannot compile it because it doesn't find the files.