// 22.5HV2 Software Engineering II
// Unit 1 Exercise 2

#include <iostream.h>
#include <iomanip.h>
#include <stdlib.h>    // needed for srand(), rand() and atoi()
#include <time.h>      // needed for time()

void draw(int[]);
void check(int[],int[],int[]);
void sort(int[],int);

int main(int argc, char *argv[])
{
   unsigned long  n, n_tickets;   // unsigned long allows us a large +ve integer
   int            i, ticket[6], balls[6], matches[7];

   srand(int(time(NULL)));  // seed random number generator with time

   if ( argc!=2 ) {
      cerr << "USAGE: ex2 no_of_tickets" << endl;
      return 1;
   }
   // NOTE: You will have to select a LOT of tickets to accurately estimate probabilities (~10000000)
 
   n_tickets = atoi(argv[1]);

   for (i=0;i<7;i++) matches[i] = 0;  // initialise matches

   for (n=0;n<n_tickets;n++) {
      draw(ticket);
      draw(balls);
      check(ticket,balls,matches);
   }

   for (n=0;n<7;n++)
      cout << "probability of " << n << " matches = " << matches[n]/float(n_tickets) << endl; 

}

void draw(int t[])
{
   int  i, j;
   bool flag=false;

   for (i=0;i<6;i++) {
      do {
         flag = false;
         t[i] = rand()%49+1;  // generate random number in range 1-49
         for (j=0;j<i;j++)
            if ( t[i] == t[j] ) { flag=true; break; }  // has ball already been drawn?
      } while (flag);
   }

   sort(t,6);  // sort into ascending order
}

void check(int t[], int b[], int m[])
{
   int i, j, n_matches=0;

   for (i=0;i<6;i++)
      for (j=0;j<6;j++)
         if ( t[i] == b[j] ) n_matches++;

   m[n_matches]++;
}

void sort(int array[], int n)  // sort algorithm for ints
{
   int    current, next, temp;
   for (current=0;current<n-1;current++) 
       for (next=current+1;next<n;next++)
           if (array[current] > array[next]) {
              temp = array[current];
              array[current] = array[next];
              array[next] = temp;
           }
}