Why not: using namespace std; map<int, vector<int>> whatever; It's a lot shorter, actually correct, and it's totally cool to import whole namespaces in a .cpp

Why not: using namespace std; map<int, vector<int>> whatever; It's a lot shorter, actually correct, and it's totally cool to import whole namespaces in a .cpp implementation file where you're likely to actually declare something like that. If you're going to critique the language you should try to learn it first.