#include "mylib.h"
#include <cassert>       // assert()
#include <cmath>
#include <iostream>
#include <functional>    // multiplies<>{}
#include <list>
#include <numeric>       // iota()
#ifdef _OPENMP
#include <omp.h>
#endif
#include <vector>
using namespace std;

double scalar(vector<double> const &x, vector<double> const &y)
{
    assert(x.size() == y.size()); // switch off via compile flag: -DNDEBUG
    size_t const N = x.size();
    double sum = 0.0;
#pragma omp parallel for default(none) shared(x,y,N) reduction(+:sum) schedule(static)
    for (size_t i = 0; i < N; ++i)
    {
        sum += x[i] * y[i];
        //sum += exp(x[i])*log(y[i]);
    }
    return sum;
}

double scalar2(vector<double> const &x, vector<double> const &y)
{
    assert(x.size() == y.size());
    size_t const N = x.size();
    double sum = 0.0;

    #pragma omp parallel shared(x,y,N,sum)
    {
        double local_sum = 0.0;

        int const th_id  = omp_get_thread_num();
        int const nthrds = omp_get_num_threads();

        for (size_t i = th_id; i < N; i += nthrds) {
            local_sum += x[i] * y[i];
        }

        #pragma omp atomic
        sum += local_sum;
    }
    return sum;
}


vector<int> reduction_vec(int n)
{ 
    vector<int> vec(n);
#pragma omp parallel default(none) shared(cout) reduction(VecAdd:vec)
    {
        #pragma omp barrier
        #pragma omp critical
        cout << omp_get_thread_num() << " : " << vec.size() << endl;
        #pragma omp barrier
        iota( vec.begin(),vec.end(), omp_get_thread_num() );
        #pragma omp barrier
        #pragma omp critical
        cout << vec << endl;
    }
    return vec;
}

vector<int> reduction_vec_append(int n)
{ 
    vector<int> vec;
#pragma omp parallel default(none) shared(cout,n) reduction(VecAppend:vec)
    {
        vector<int> local(n);
        #pragma omp barrier
        #pragma omp critical
        cout << omp_get_thread_num() << " : " << local.size() << endl;
        #pragma omp barrier
        iota( local.begin(),local.end(), omp_get_thread_num() );
        #pragma omp critical
        vec.insert(vec.end(), local.begin(), local.end());
    }
    return vec;
}