How to initialize and return vector of vectors more compactly?

Question

How to initialize and return vector of vectors more compactly? The code below seems bloated and repetitious for the two cases when K==1 and K==N .

std::vector< std::vector<unsigned int> > Foobar(const unsigned int K, const unsigned int N)
{
    std::vector< std::vector<unsigned int> > res;

    if (K == 1)
    {
        std::vector<unsigned int> r(1,N);  //One N.
        res.emplace_back(r);
        return res;
    }

    if (K == N)
    {
        std::vector<unsigned int> r(N,1);  //N ones.
        res.emplace_back(r);
        return res;
    }

    PopulateVectors(res, K+1, N+1);
    PopulateVectors(res, K, N);
    return res;
}

The function PopulateVectors() accepts res as a reference and inserts multiple vectors into it. The way it works internally is immaterial to this question.

Answer 1

if (K == 1)
{
  return {{N}};
}

if (K == N)
{
  return {std::vector<unsigned int>(N,1)};
}