//////////////////////////////////////////////////////////////////////////
//                                histogram.c                           //
//                                                                      //
// Purpose                                                              //
// =======                                                              //
// The program obtains a finite set of readings from the user           //
// and calculates the largest and smallest reading.                     //
// It then obtains from the user the number of intervals                //
// for a histogram and calculates how many readings fall into           // 
// each interval between Min and Max                                    //                
// The readings are temporarily stored in an array.                     //
// The reading counts in each interval are also stored in an array      //
// A C++ built-in array is used                                         // 
//                                                                      //
//                                                                      //
// Author            Creation Date                                      //
// ======            =============                                      //
// AY                2 November 2004                                    //
//                                                                      //
// Input/Output                                                         //
// ============                                                         //
// The input is the number of readings (int), the readings (double)     //
// and the number of intervals between Min and Max                      //
// The input is expected to be from the keyboard                        // 
// The output is the largest (double) and smallest reading (double)     //
// as well as the reading counts in each interval (histogram)           //             
//                                                                      //
//////////////////////////////////////////////////////////////////////////

#include <iostream>
using namespace std;


int main()
{
 
 const int MAXSIZE=100; // absolute max size of the array 	
 double readings[MAXSIZE]; // array declaration
 int hist [MAXSIZE];
 
 int noOfReadings; // actual number of readings 
 int noOfIntervals; // actual number of intervals 

 int carryon = 1; // initialise flag to continue calculations
 while (carryon)
 {

  cout << "Enter actual number of temperature readings (0<n<=" 
       << MAXSIZE << "): ";
  cin >> noOfReadings; cout << endl;
 
  cout << "Enter actual number of intervals for a histogram (0<k<=" 
       << noOfReadings << "): ";
  cin >> noOfIntervals; cout << endl;

  // enter actual readings from keyboard
  cout << "Enter your readings, one at a time, following the prompt\n";
  for (int i = 0; i < noOfReadings; i++)
  {
  
    cout << "reading(" << i+1 << ") = ";
    cin >>  readings[i];
   
  }                      
  cout << endl;
   
   // find max and min
   // initialise current max and min
  double maxRead = readings[0];
  double minRead = readings[0]; 
  
  for (int i = 1; i < noOfReadings; i++)
  {
  
     if (maxRead < readings[i])
     {
        maxRead = readings[i];
     }
     
     if (minRead > readings[i])
     {
         minRead = readings[i];
     }    
   
  }

   // compute the histogram

   // size of interval
   double  d = (maxRead - minRead)/noOfIntervals;
   cout << "d=" << d << endl;
    // initialise this histogram first
  for (int i = 0; i < noOfIntervals; i++)
  {
    hist[i] = 0;
  }

   // look through each reading and increment the appropriate interval count
  int offset;
  for (int i = 0; i < noOfReadings; i++)
  {
    offset = int((readings[i]-minRead)/d);
    if (offset < noOfIntervals)
    { 
      hist[offset]=hist[offset]++;
    }
    else
    {
      hist[offset-1]=hist[offset-1]++;
    }

    cout << "offset=" << offset << endl;  
  }  
  // output the results
   
  cout << "The largest reading was " << maxRead << endl;
  cout << "The smallest reading was " << minRead << endl;

  cout << "Now the numbers of readings in each interval between max and min: " 
       << endl; 
  for(int i=0; i < noOfIntervals; i++)
  {
    cout << "Interval(" << i+1 << ")= " << hist[i] << endl;
  }

 cout << endl << "Do you want to continue? (type 1 if yes; 0 if not) ";
 cin >> carryon;
}
  cout << "End of Readings" << endl;
  return 0;
} // end main()