/// <summary>
/// Swaps three randomly chosen elements of the given <paramref name="permutation"/> array.
/// </summary>
/// <exception cref="ArgumentException">Thrown when the <paramref name="permutation"/> contains less than 3 elements.</exception>
/// <remarks>
/// It is implemented such that first 3 positions are randomly chosen in the interval [0;N) with N = length of the permutation with all positions being distinct from each other.
/// Then position 1 is put in place of position 3, position 2 is put in place of position 1 and position 3 is put in place of position 2.
/// </remarks>
/// <param name="random">The random number generator.</param>
/// <param name="permutation">The permutation to manipulate.</param>
public static void Apply(IRandom random, Permutation permutation)
{
if (permutation.Length < 3)
{
throw new ArgumentException("Swap3Manipulator: The permutation must be at least of size 3.", "permutation");
}
int index1, index2, index3;
do
{
index1 = random.Next(permutation.Length);
index2 = random.Next(permutation.Length);
index3 = random.Next(permutation.Length);
} while (index1 == index2 || index2 == index3 || index1 == index3);
permutation.Swap(index1, index2);
permutation.Swap(index2, index3);
}
public static void Apply(Permutation permutation, int index1, int index2)
{
permutation.Swap(index1, index2);
}