#include <stdio.h>
#include <stdlib.h>
#include <omp.h>

#define ARRAY_SIZE 1000000
#define REPEAT     1000

double* gen_array(int n) {
    double* array = (double*) malloc(n*sizeof(double));
    for(int i=0; i<n; i++) {
        array[i] = rand()%1000;
    }
    return array;
}

double dotp(double* x, double* y) {
    double global_sum = 0.0;
    #pragma omp parallel
    {
        #pragma omp for
        for(int i=0; i<ARRAY_SIZE; i++) {
            #pragma omp critical
            global_sum += x[i] * y[i];
        }
    }
    return global_sum;
}

double oracle(double* x, double* y) {
    double sum = 0.0;
    for (int i = 0; i < ARRAY_SIZE; i++) {
        sum += x[i] * y[i];
    }
    return sum;
}

int main() {
    // Generate input vectors
    double *x = gen_array(ARRAY_SIZE);
    double *y = gen_array(ARRAY_SIZE);
    double result, answer;
    answer = oracle(x, y);

    // Test framework that sweeps the number of threads and times each ru
    double start_time, run_time;
    int num_threads = omp_get_max_threads();
    for(int i=1; i<=num_threads; i++) {
        omp_set_num_threads(i);
        start_time = omp_get_wtime();
        for(int j=0; j<REPEAT; j++) {
            result = dotp(x,y);
            if (result != answer) {
                printf("Incorrect dotp %f %f\n", result, answer);
                return 0;
            }
        }
        run_time = omp_get_wtime() - start_time;
        printf(" %d thread(s) took %f seconds\n",i,run_time);
    }
}