Vector of Vectors to create matrix

You have to initialize the vector of vectors to the appropriate size before accessing any elements. You can do it like this:
// assumes using std::vector for brevity
vector> matrix(RR, vector(CC));

This creates a vector of RR size CC vectors, filled with 0.

As it is, both dimensions of your vector are 0.
Instead, initialize the vector as this:
vector > matrix(RR);
for ( int i = 0 ; i < RR ; i++ ) matrix[i].resize(CC); This will give you a matrix of dimensions RR * CC with all elements set to 0.