#include <iostream>
#include <omp.h>

using namespace std;

int MySum(int a, int b) {
   return a+b;
}


int main() {
    int sum{0};

    for( int j = 2; j < 10; ++j) {
       sum = 0;
       #pragma omp parallel
       {
           #pragma omp for reduction (+: sum)
           for(int i = 1; i <= j; ++i) {
             sum += i;
           }
        }
        cout << "The sum to " << j << " is " << sum << endl;
    }

    cout << endl << endl;

    int maxValue{-1};
    #pragma omp parallel reduction (max: maxValue)
    {
        int id{omp_get_thread_num()};
        unsigned int seed{(id+1) * static_cast<unsigned int>(time(nullptr))};

        for(int i = 1; i < 3; ++i) {
           int tmpValue = rand_r(&seed) % 1000;
           maxValue = max(maxValue, tmpValue);

           #pragma omp critical 
           cout << "\t" << id << " has " << tmpValue << endl;
        }

       #pragma omp barrier

       #pragma omp critical 
       {
          cout << endl;
          cout << "Thread " << id << " has " << maxValue << endl;
       }

    }

    cout << "The max value is " << maxValue << endl;

    cout << endl << endl;

    sum = 0;
    #pragma omp declare reduction \
        (mySum: int : omp_out = omp_in + omp_out) \
        initializer(omp_priv = 0)
     { 
       #pragma omp parallel
       {
           #pragma omp for reduction (mySum: sum)
           for(int i = 1; i <= 10; ++i) {
             sum += i;
           }
       }
     }
     cout << "The sum is " << sum << endl;

     cout << endl << endl;

    sum = 0;
    #pragma omp declare reduction \
        (sumFun: int : omp_out = MySum(omp_out, omp_in)) \
        initializer(omp_priv = 0)
    #pragma omp parallel
    {
        #pragma omp for reduction (sumFun: sum)
        for(int i = 1; i <= 10; ++i) {
             sum += i;
        }
    }
    cout << "The sum is " << sum << endl;

    return 0;
}