// MA 4990-01 Special Topics in Probability
// Instructor:  Dr. Zhijun Liu
// Program Author:  Reggie Warren

#include <stdlib.h>
#include <stdio.h>
#include <iostream.h>
#include <string.h>
#include <fstream.h>

// function prototype
// 
int getVals(int numVals);

int main(int argc, char* argv[])
{
   int *sum = new int[atoi(argv[1])];
   int input;
   int max = 0;
   int min = 0;
   int count = 0;
   ofstream outFile("output.txt");
   ifstream inFile;

   // Make sure that the number of trials and the sequence size are passed
   // as command line arguments
   //
   if(argc != 3)
   {
      cerr << "Invalid number of arguments--please enter at least two" << endl;
      exit(1);
   }

   // Loop through calling the procedure that will generate the sum of the
   // random numbers a number of times equal to the command-line specified
   // value.  Write the sums to a file.
   //
   for(int i = 0; i < atoi(argv[1]); i++)
   {
      sum[i] = getVals(atoi(argv[2]));   
      outFile << sum[i] << endl;
   }

   outFile << endl;
   for(int i = 0; i < atoi(argv[1]); i++)
   {
      // figure out range of values--expensive for large 'sum' arrays
      //
      if(sum[i] > max)
         max = sum[i];
      
      if(sum[i] < min)
         min = sum[i];

      // find out number of times a particular sum occurs
      //
      if(i > 0)
      {
         // check for matching value--rather expensive for large 'sum' arrays
         //
         for(int j = atoi(argv[1]); j > 0; j--)
         {
            if(sum[i] == sum[j])
              count++;
         }
         outFile << "Value " << sum[i] << " occurs " << count << " times."
                 << endl;
         
         // reset the count variable
         //
         count = 0;
      } // end if statement   
   } // end for loop
   outFile << endl << "Range:  [" << min << ',' << max << ']' << endl;
   // Take care of possible memory leaks and dangling pointers
   //
   delete [] sum;
   sum = NULL;

} // end main
   
int getVals(int numVals)
{
   int* intArray = new int[numVals];
   int sum = 0;
   
   // fake randomness--rand() generates numbers between 0 and 2^15 - 1,
   // if rand() returns a value greater than the value corresponding to
   // half this range, the corresponding array element equals 1; else, 
   // it equals zero
   //
   for(int i = 0; i < numVals; i++)
   {
      if(rand() > 16384)
         intArray[i] = 1;
      
      else
         intArray[i] = -1;
      
      // calculate sum
      //
      sum += intArray[i];

      // cout << sum << "            " << intArray[i] << endl;
   }
   
   return sum;
}