#pragma once
#include <cassert>
#include <vector>
using namespace std;


// Counts number of possible decompositions with 2 primes that sum up to k.
int single_goldbach_par(int k);

// Counts number of possible decompositions with 2 primes that sum up to k for all even numbers k \in {4,...,n}.
vector<int> count_goldbach_par(int n);

// Prints all decompositions of k.
void print_decomps(int k);


/** 	 Vector @p b adds its elements to vector @p a .
	@param[in] a	vector
	@param[in] b	vector
	@return 	     a+=b componentwise
*/
template<class T>
std::vector<T> &operator+=(std::vector<T> &a, std::vector<T> const &b)
{
    assert(a.size()==b.size());
    for (size_t k = 0; k < a.size(); ++k) {
        a[k] += b[k];
    }
    return a;
}

#pragma omp declare reduction(VecAdd : std::vector<int>  : omp_out += omp_in) \
 initializer (omp_priv=omp_orig)