I have a vector of 2D points (N elements) in the plane. I want to
make the convex hull of these points. After that, I want to retrieve the
vector index of each vertex in the convex hull.
I know that, there is such possibility for triangulation by making use of vector<pair<Point_2, unsigned> >, but when I use paired point in making convex hull, it produces a bunch of errors. how can I do this?