#include <algorithm>
#include <vector>


struct Student {
    int get_average() const {
        return 42;
    }
};

struct CompAverage
{
    bool operator () (const Student & a, const Student & b) const
    {
        return a.get_average() < b.get_average();
    }
};

using Student_IT = std::vector<Student>::const_iterator;

Student dispatch(const std::vector<Student> &all_students, Student_IT (*f)(Student_IT, Student_IT, CompAverage))
{
    return *f(std::begin(all_students), std::end(all_students), CompAverage{});
}

int main()
{
    std::vector<Student> v(42);

    dispatch(v, &std::min_element);
    dispatch(v, &std::max_element);
    return 0;
}