// This is a function that returns the index
// indicating the location of a value in the
// array A. This version terminates early if
// the value is found.
//
// Precondition: A is sorted in ascending order
//   and contains N elements
// Postcondition: If the value is in A, its index
//   is returned. If the value is not found, a
//   -1 is returned instead.

int BinSearch1 (int A[], int N, int value)
{
 int min, max, mid;

 min = 0;
 max = N - 1;

 while (min <= max)
 {
  mid = (min + max)/2;
  if (A[mid] == value)
   return mid;
  if (value < A[mid])
   max = mid - 1;
  else
   min = mid + 1;
 }

 return -1;
}



// This is a function that returns the index
// indicating the location of a value in the
// array, A. It does not terminate early if the
// value is found - this saves one comparison each
// iteration, and is actually more efficient on average
// compared to the early termination version.

// Precondition: A is sorted in ascending order 
//   and contains N elements.
// Postcondition: If the value is in A, found is 'true'
//   and the index of the element is returned in index. If
//   the value is not in A, found is 'false' and index contains
//   the location where value should be, relative to the other
//   elements in A

void BinSearch2 (int A[], int N, int value,  int& index, int& found)
  {
   int min, max, mid;

   min = 0;
   max = N - 1;

   while (min <= max)
     {
      mid = (min + max)/2;
      if (value < A[mid])
         max = mid - 1;
      else
         min = mid + 1;
     }
   index = mid;
   found = (A[index] == value);
}