q2.cpp

// Competency test question 2
//
//Provide a function receiving an integer (X) and a tuple (std::tuple<type1, type2, type3…>) into a tuple of vectors (std::tuple<std::vector,std::vector, std::vector, …> where each vector has X elements of each originally received in each tuple_element. E.g. for X=2 and the tuple {1, 1.0, ‘a’} , the result type is std::tuple<std::vector, std::vector, std::vector> and the values are: {{1, 1},{1.0, 1.0},{‘a’, ‘a’}}
//
// Gets the first value, makes a vector with it's x copies, makes a tuple
// of it, and caoncats it with the tuple of vectors of rest of the values
#include <iostream>
#include <tuple>
#include <vector>

using namespace std;

template < std::size_t... N , typename... T >
auto tail_impl( std::index_sequence<N...> , std::tuple<T...> t ) {
   return  std::make_tuple( std::get<N+1>(t)... );
}

template <class F, class... R >
tuple<R...> tail( std::tuple<F,R...> t ) {
   return  tail_impl( std::make_index_sequence<sizeof...(R)>() , t );
}

template<class... T>
tuple<vector<T>...> func(int, tuple<T...>);

template<class F, class... T>
tuple<vector<F>,vector<T>...> func(int x, tuple<F,T...> t) {
    vector<F> f;
    F val = get<0>(t);
    for(int i=0;i<x;i++) {
        f.push_back(val);
    }
    return tuple_cat(make_tuple(f),func(x,tail(t)));
}

template<>
tuple<> func<>(int x, tuple<> t) {
    return tuple<>();
}

template <class T>
int tuple_length(T t) {
    return std::tuple_size<T>::value;
}

template<class T>
void print_vec(vector<T> v) {
    for(auto& x:v) {
        cout << x << ' ';
    }
    cout << endl;
}

int main() {
    auto a = func(4,make_tuple(3,"er",5.45,'s'));
    cout << tuple_length(a) << endl;
    print_vec(get<0>(a));
    print_vec(get<1>(a));
    print_vec(get<2>(a));
    print_vec(get<3>(a));
}