#include <omp.h>
#include <stdio.h>
#include <stdlib.h>
#include<sys/time.h>
#include<time.h>

#define SIZE 100000000

void print_duration(struct timespec *b, struct timespec *c)
{
        long long r = c->tv_nsec - b->tv_nsec;
        r += ((long long)(c->tv_sec - b->tv_sec) ) * 1000000000;
        printf("duration = %lld nanoseconds\n", r);
}


int main(int argc, char * argv[])
{
	int N;
	int i, j, k;
	struct timespec bb, ee;
        double *a, *b, *c;

	if (argc > 1) N = atoi(argv[1]);
	else N = 100;

        a = (double *)malloc(sizeof(double)*N);
        b = (double *)malloc(sizeof(double)*N);
        c = (double *)malloc(sizeof(double)*N);

	#pragma omp parallel
	{
                #pragma omp single
	        {
			printf("%d threads.\n", omp_get_num_threads());
		}
        }
	

	//#pragma omp parallel for private(i) shared(a, b, c, N)
		for (i=0 ;i<N; i++)  {
		        c[i] = 0;
			a[i] = drand48();
			b[i] = drand48();
	        }


        clock_gettime(CLOCK_THREAD_CPUTIME_ID, &bb);  

        #pragma omp parallel private(i, j) num_threads(2)
	{
                // copy 
		for (j =0; j<10; j++) {
#pragma omp parallel for private(i) shared(a, b, c, N) 
		        for (i=0; i<N; i++)
				c[i] = a[i];
                } 
        }
        clock_gettime(CLOCK_THREAD_CPUTIME_ID, &ee);  
        print_duration(&bb, &ee);


}