taste_the_rainbow

#include <stdlib.h> // rand()
#include <stdio.h> //io (printf)
#include <time.h> // time(NULL)
#include <omp.h> // Multi threading lib

#define rTHRDS 8 // Number of threads to request
#define N 1000 // Array size for the array of opened bags, determined through experimentation
#define COLORS 5 // Number of colors in a bag
#define SKITTLES 60 // Number of skittles in a bag


// This function generates 5 numbers that add to 60
// Then concatenaets them into a single integer value
double fillbag()
{
    int arr[COLORS] = {0}; // 5 element array to store number of occurences of 5 colors
    for(int i = 0; i < SKITTLES; i++)
    {
        arr[rand()%COLORS]++; // A value 0-5 is generated, and that element in the array is incremented
    }
    // This will hold the unique integer value associated with
    // this bag of skittles
    unsigned long long int bagsumvalue = 0;
    // This will create an integer value from
    // color values - 12,13,14,15,16 becomes 12131.41516
    bagsumvalue = arr[0]*100000000+arr[1]*1000000+arr[2]*10000+arr[3]*100+arr[4];
    return bagsumvalue/100000.00;
}

// This function takes pointer values to the variables that track and calculate
// the running average, and using the values of the most recently discovered double
// updates them all, returning the newly calculated average
double updateAverage(long long int *sob, double *df, int nv)
{
    // By adding the most recent number of bags opened to find a double to the total number of bags opened
    // and divinding by the current number of duplicates found, we are able to calculate the most recent
    // average number.
    *sob+=nv;
    ++*df;
    return *sob / *df;
}
// This function sets the value pointed to by its argument to 0 (uneccessary but left in from
// previous versions for code readability)
void reset(unsigned long long int *bo)
{
    *bo = 0;
}


int main()
{
    double opened[N]; // Array to store opened bags for searching
    double * ptr = (double*)calloc(N, sizeof(double));
    ptr = opened;
    unsigned long long int bags_opened = 0; // Current number of bags opened , changes when new duplicates found
    unsigned long long int sum_of_bags = 0; // Number of total bags opened
    double doubles_found = 0; // Number of doubles found so far
    double running_average = 0; // Running average number of bags opened to find doubles
    ; // Making several bags at a time

    int match = 0; // Flag for checking if match found
    srand(time(NULL)); // Seeding time
    omp_set_num_threads(rTHRDS); // Request a number of threads
    int ID; // Declaring the thread ID variable for use below
    const int epstein_didnt_kill_himself = 1; // Since the while loop will run indefinitly, a const non zero int value is used

    while (epstein_didnt_kill_himself) // Infinite loop since value of argument is always (1) true
    {
        opened[bags_opened] = fillbag(); // Newly filled bag placed in array at 0 or after most recent bag determined not to have a duplicate
        match = 0; // Match flag used to signal to all threads when a duplicate has been found
        #pragma omp parallel for num_threads(8) private(ID) shared(match) schedule(static, 8 ) // All threads have their own ID but share access to match
        for(int i =0; i < bags_opened;i++) // Iterate over array but stopping prior to index of most recently added bag (the one we eill be comparing)
        {
            ID = omp_get_thread_num(); // Initialize thread ID
             if(match) // If match flag set, thread does no calculation for remaining iterations (cannot use break in parallel for loop)
            {
                continue;
            }
            else if(opened[bags_opened]==opened[i]) // Check the most recently added (opened) bag against all others
            {
                // Update running average and incrememnting bags_opened for calculation
                running_average = updateAverage(&sum_of_bags, &doubles_found, ++bags_opened);
                // Set flag so that other threads stop comparing (break does not work in omp loops)
                match = 1;
                // Every 5000 duplicates output the average (Takes between 1 and 2 seconds)
                if((int)doubles_found%5000==0) {printf("******\nAverage: %f\nOpened: %lld\nDuplicates : %d\n", running_average,sum_of_bags, (int)doubles_found);}
                // Reset number of bags opened to begin again
                reset(&bags_opened);
            }
        }
        if(!match) // In the case that the most recenlty bag added does not match
        {
            // Increment variable to track bags placed into opened array
            bags_opened++;
        }
    }
     return 0;

}