public bool MoveNext()
{
if (reseted)
{
this.current = this.parent;
this.reseted = false;
return this.current != null;
}
if (this.current == null)
throw new InvalidOperationException("Enumeration already finished");
this.current = this.current.GetSuccessor();
return this.current != null;
}
public void Reset()
{
this.reseted = true;
this.current = null;
}
/// <summary>
/// Creates the next permutation in lexicographic order.
/// </summary>
/// <returns>
/// The next <see cref="Permutation"/> instance if there remain any;
/// otherwize a null reference.
/// </returns>
public Permutation GetSuccessor()
{
Permutation result = new Permutation(this.order);
int left, right;
for (int k = 0; k < result.order; ++k) // Step #0 - copy current data into result
{
result.data[k] = this.data[k];
}
left = result.order - 2; // Step #1 - Find left value
while ((result.data[left] > result.data[left + 1]) && (left >= 1))
{
--left;
}
if ((left == 0) && (this.data[left] > this.data[left + 1]))
return null;
right = result.order - 1; // Step #2 - find right; first value > left
while (result.data[left] > result.data[right])
{
--right;
}
int temp = result.data[left]; // Step #3 - swap [left] and [right]
result.data[left] = result.data[right];
result.data[right] = temp;
int i = left + 1; // Step #4 - order the tail
int j = result.order - 1;
while (i < j)
{
temp = result.data[i];
result.data[i++] = result.data[j];
result.data[j--] = temp;
}
return result;
}
public PermutationEnumerator(Permutation parent)
{
if (parent == null)
throw new ArgumentNullException("parent");
this.parent = parent;
}
public void K2N5()
{
Permutation p = new Permutation(5);
ShowPermutation(p);
}
public void Identity2()
{
Permutation p = new Permutation(2);
ShowPermutation(p);
}
private static void ShowPermutation(Permutation p)
{
int i = 0;
foreach (Permutation s in p.GetSuccessors())
Console.WriteLine("{0}: {1}", i++, s);
}
public void K2N5()
{
Permutation p = new Permutation(5);
ShowPermutation(p);
}
public void Identity2()
{
Permutation p = new Permutation(2);
ShowPermutation(p);
}