how to assign type of cell in vector

Question

I am working on a C++ project which is about simulating bees in an ecosystem. We had to code an environment represented via a vector of seeds outside of the class :

Now we must make sure that each of these seeds transmits its nature (Kind : Rock, Water, Grass) to the cell of the one-dimensional array cells_ whose position it occupies. Clearly, if the seed has for position (x,y) and for nature k then the cell at position (x,y) must take the value k, except if it is a water cell (water cells do not change their nature, cannot be covered).

here are the attributs in private (among others) :

    enum class Kind : short { Grass, Water, Rock };
    std::vector<Kind>cells_;
    struct Seed { sf::Vector2i position_;}; 
std::vector<Seed> seeds_; 
int nbCells_; // represents the number of cells per line
    // uniform() is a method that attributes random coordinates for a seed 


class World {
//...
            
    private:
    int nbCells_;
    float cell_size_;

//and here is the body of the method we have to code 
    
    for (unsigned int i(0); i < nbCells_-1; ++i ) { 
           position_ =  uniform(0, nbCells_-1); }
           if (cells_[i] == position_) {
               switch Kind::i {
                   case Kind::Rock:
                   .cells_[i] = position_;
                   break;

                   case Kind::Grass:
                   .cells_[i] = position_;
                   break;

 
};

but I'm struggling with the syntax ... any ideas ? thanks !