#include <iostream>
using namespace std;

/*
 * Searches the array anArray[first] through anArray[last]
 *  for value by using a binary search.
 * @pre 0 <= first, last <= SIZE - 1, where SIZE is the
 *      maximum size of the array, and anArray[first] <=
 *      anArray[first + 1] <= ... <= anArray[last].
 * @post None.
 * @param anArray  The array to search.
 * @param first  The low index to start search from.
 * @param last  The high index to stop searching at.
 * @param value  The search key.
 * @return If value is in anArray, the function returns the
 *         index of the array item that equals value;
 *         otherwise the function returns -1.
 */
int binarySearch(const int anArray[], int first,
		 int last, int value)
{
   int index;
   if (first > last)
      index = -1;      // value not in original array

   else
   {
      int mid = (first + last)/2;
      if (value == anArray[mid])
	 index = mid;  // value found at anArray[mid]

      else if (value < anArray[mid])
	 index = binarySearch(anArray, first, mid-1, value);

      else
	 index = binarySearch(anArray, mid+1, last, value);
   }
   return index;
}


int main()
{
  int index;
  int array[] = {2, 5, 7, 8, 9, 34, 54, 91, 103, 104, 999, 1062, 3387};

  cout << "Array is: ";
  for(int i=0 ; i<13 ; i++)
    cout << array[i] << " ";
  cout << endl;
  
  cout << "Search for 2: ";
  if((index = binarySearch(array, 0, 13, 2)) >= 0)
    cout << "Found at index " << index;
  else
    cout << "Not found";
  cout << endl;

  cout << "Search for 56: ";
  if((index = binarySearch(array, 0, 13, 56)) >= 0)
    cout << "Found at index " << index;
  else
    cout << "Not found";
  cout << endl;

  cout << "Search for 91: ";
  if((index = binarySearch(array, 0, 13, 91)) >= 0)
    cout << "Found at index " << index;
  else
    cout << "Not found";
  cout << endl;

  return 0;
}