#include <iostream>
using namespace std;

// merge function prototype
template <class Type>
void merge(Type* array, Type* tempArray, int low, int middle, int high);

// merge sort helper prototype
template <class Type>
void mergeSortHelper(Type* array, Type* tempArray, int low, int high);

// merge sort prototype
template <class Type>
void mergeSort(Type* array, int size);

template <class Type>
void merge(Type* array, Type* tempArray, int low, int middle, int high) 
{
     int i, j, k;

     for (i = low; i <= high; i++)  
     { 
          // copy into temp array
          tempArray[i] = array[i]; 
     } 

      i = low;      //indices into subarrays
      j = middle+1; 
      k = low;      //indices into output array

      while ((i <= middle) && (j <= high))  
      {	
          if (tempArray[i] <= tempArray[j])		// if lhs item is smaller
	          array[k++] = tempArray[i++];		// put in final array, increment
          else					               // final array position, lhs index
	          array[k++] = tempArray[j++];		// else put rhs item in final array
      }						               // increment final array position
						                    // rhs index

     // at this point, one of the two arrays has been consumed
     while (i <= middle)
          array[k++] = tempArray[i++];		// copy the rest of the data
}						               // only need to copy if in lhs 
                    					// rhs array already in right place
template <class Type>
void mergeSortHelper(Type* array, Type* tempArray, int low, int high)
{
     if (low < high)
     {
          int middle = (low + high) / 2;
          mergeSortHelper(array, tempArray, low, middle);
          mergeSortHelper(array, tempArray, middle+1, high);
          merge(array, tempArray, low, middle, high);
     }
}

template <class Type>
void mergeSort(Type* array, int size)
{
     Type* tempArray = new Type[size];
     mergeSortHelper(array, tempArray, 0, size-1);
     delete [] tempArray;
}


int main(int argc, char* argv[])
{
     int i;
     int size = 5;
     int* data = new int[5];
     
     data[0] = 9; data[1] = 8; data[2] = 7; data[3] = 6; data[4] = 5;

     cout << "Unsorted data: " << endl;
     for (i = 0; i < size; i++)
     {
          cout << data[i] << endl;         
     }
     mergeSort(data,size);
     cout << "Sorted data: " << endl;
     for (i = 0; i < size; i++)
     {
          cout << data[i] << endl;         
     }

     double* data2 = new double[5];
     
     data2[0] = 9.2; data2[1] = 8.5; data2[2] = 8.4; data2[3] = 6.2; data2[4] = 5.1;

     cout << "Unsorted data: " << endl;
     for (i = 0; i < size; i++)
     {
          cout << data2[i] << endl;         
     }
     mergeSort(data2,size);
     cout << "Sorted data: " << endl;
     for (i = 0; i < size; i++)
     {
          cout << data2[i] << endl;         
     }
}