#include <iostream>
#include "mayer_primes.h"
#include <vector>
#include <algorithm>
#include "timing.h"
#include "omp.h"
using namespace std;



vector<unsigned int> count_goldbach(unsigned int n)
{
    vector<unsigned int> primes = get_primes(n);
    size_t npr = primes.size();
    int nthreads = omp_get_max_threads();

    vector<vector<unsigned int>> local_counts(nthreads, vector<unsigned int>(n+1, 0));

    #pragma omp parallel
    {
        int tid = omp_get_thread_num();
        auto &lc = local_counts[tid];

    #pragma omp for schedule(static)
        for (int j = 0; j < (int)npr; ++j)
        {
            unsigned int p = primes[j];
            for (unsigned int i = j;i < primes.size() && p + primes[i] <= n; ++i)
            {
                unsigned int q = primes[i];
                unsigned int s = p + q;

               lc[s] +=1;
            }
        }
    }

    // combine
    vector<unsigned int> counts(n+1, 0);
    for (int t = 0; t < nthreads; ++t)
        for (unsigned int k = 0; k <= n; ++k)
            counts[k] += local_counts[t][k];

    return counts;
}




int main()
{   

    

    //3
    vector<unsigned int> counts = count_goldbach(100000);
    cout << (max_element(counts.begin(), counts.end()) - counts.begin()) << endl; 

    //4
    vector<unsigned int> nvalues = {10000, 100000, 400000, 1000000, 2000000};
    double time;
    unsigned int n;
    for(unsigned int i = 0; i< nvalues.size(); i++)
    {
        n = nvalues.at(i);
        tic();
        count_goldbach(n);
        time = toc();
        cout << "Time for n=" << n << ": " << time << endl;
    }
 




    return 0;
}