/// <summary>
/// Return ith smallest element of the array[p...r]
/// </summary>
public static int RSelect(int[] array, int p, int r, int i)
{
if (p == r)
{
return(array[p]);
}
int pivotIndex = Quick.Partition(array, p, r);
int k = pivotIndex - p + 1;
if (i <= k)
{
return(RSelect(array, p, pivotIndex, i));
}
else
{
return(RSelect(array, pivotIndex + 1, r, i - k));
}
}
