private static VariableLetterGroup RankLetters(VariableLetterGroup letters)
{
VariableLetterGroup copy = new VariableLetterGroup(letters);
VariableLetterGroup res = new VariableLetterGroup();
while (copy.Length() > 0)
{
res.Add(new Letter(copy[0].GetLetter()));
int i = 1;
int rank = 1;
while (i < copy.Length())
{
if (copy[i] == copy[0])
{
res.Add(new Letter(copy[i].GetLetter(), rank));
copy.RemoveAt(i);
rank++;
}
else
{
i++;
}
}
copy.RemoveAt(0);
}
return(res);
}
public static IEnumerable <VariableLetterGroup> UniquePermutations(VariableLetterGroup letters)
{
VariableLetterGroup vlg = RankLetters(letters);
foreach (VariableLetterGroup v in Permutations(vlg))
{
VariableLetterGroup copy = new VariableLetterGroup(v);
bool copy_is_consumed = false;
while (!copy_is_consumed)
{
int i = 0;
int j = 1;
bool permutation_is_valid = true;
while (j < copy.Length())
{
if (copy[j] == copy[i])
{
// we suppose the job is well done : unique rank for each identical letter
if (copy[j].GetRank() > copy[i].GetRank())
{
copy.RemoveAt(i);
i = j - 1;
}
else
{
permutation_is_valid = false;
break;
}
}
else
{
j++;
}
}
if (!permutation_is_valid)
{
break;
}
copy.RemoveAt(i);
if (copy.Length() == 0)
{
copy_is_consumed = true;
}
}
if (copy_is_consumed)
{
yield return(v);
}
}
}
public bool IsOrderedAccordingToLetterRanks()
{
VariableLetterGroup copy = new VariableLetterGroup(this);
bool permutation_is_valid = false;
while (!permutation_is_valid)
{
int i = 0;
int j = 1;
bool analyzed_letter_is_well_ordered = true;
while (j < copy.Length())
{
if (copy[j] == copy[i])
{
// we suppose the job is well done : unique rank for each identical letter
if (copy[j].GetRank() > copy[i].GetRank())
{
copy.RemoveAt(i);
i = j - 1;
}
else
{
analyzed_letter_is_well_ordered = false;
break;
}
}
else
{
j++;
}
}
if (!analyzed_letter_is_well_ordered)
{
break;
}
copy.RemoveAt(i);
if (copy.Length() == 0)
{
permutation_is_valid = true;
}
}
return(permutation_is_valid);
}
public static IEnumerable <VariableLetterGroup> Permutations(VariableLetterGroup letters)
{
int letters_length = letters.Length();
for (int i = 0; i < letters_length; i++)
{
if (letters_length == 1)
{
yield return(letters);
}
else
{
VariableLetterGroup res = new VariableLetterGroup(letters[i]);
VariableLetterGroup vlg_to_permute = new VariableLetterGroup(letters);
vlg_to_permute.RemoveAt(i);
foreach (VariableLetterGroup vlg_permuted in Permutations(vlg_to_permute))
{
yield return(res + vlg_permuted);
}
}
}
}