Best way to extract a subvector from a vector?

vector::const_iterator first = myVec.begin() + 100000;
vector::const_iterator last = myVec.begin() + 101000;
vector newVec(first, last);

It’s an O(N) operation to construct the new vector, but there isn’t really a better way.

Just use the vector constructor.
std::vector data();
// Load Z elements into data so that Z > Y > X

std::vector sub(&data[100000],&data[101000]);