private static void CompareChooseKfromN(int chooseK, int fromN, CombinatoricMode mode)
{
var tst1 = Combinatorics.ChooseKfromN(chooseK, fromN, mode).ToArray();
var tst2 = Combinatorics.ChooseKfromN(chooseK, fromN, mode); // enter alternative-call here
Compare(tst1, tst2);
}
private void ApplyNumeric(int chooseK, int fromN, CombinatoricMode mode)
{
var sb = new StringBuilder();
var counter = 0;
foreach (var result in Combinatorics.ChooseKfromN(chooseK, fromN, mode))
{
sb.Append(string.Concat(result)).Append(" ");
counter += 1;
}
txtOutput.Text = string.Concat(Preambel(chooseK, fromN, mode), counter, " results\n\n", sb.ToString());
}
private void Apply2Words(int chooseK, int fromN, CombinatoricMode mode)
{
//demo, how to transform the int-results to any other DataType: Just take them as Indicees of an Source-Element-Array (of any type).
var sb = new StringBuilder();
var words = _rgxWords.Split(txtInput.Text.Trim());
if (words.Length != fromN)
{
MessageBox.Show("number of words must equal the fromN-Parameter");
return;
}
var counter = 0;
foreach (var result in Combinatorics.ChooseKfromN(chooseK, fromN, mode))
{
sb.AppendLine(string.Join(" ", result.Select(i => words[i]).ToArray()));
counter += 1;
}
txtOutput.Text = string.Concat(Preambel(chooseK, fromN, mode), counter, " results\n\n", sb.ToString());
}
public static IEnumerable<int[]> ChooseKfromN(int chooseK, int fromN, CombinatoricMode mode) {
var ubound = chooseK - 1;
var nMax = fromN - 1;
int iPivot = 0;
switch (mode) {
case CombinatoricMode.Combination_NoRepetition: // keeps the resultSet asc-ordered
var resultSet = Enumerable.Range(0, chooseK).ToArray(); // init resultSet with ascending sequence
do {
for (var n = resultSet[ubound]; n <= nMax; n++) { // 1) output-loop: enumerate last digit and yield results
resultSet[ubound] = n;
yield return resultSet.ToArray();
}
// 2) find incrementable pivot-element: must have a gap to its successor
for (iPivot = ubound; iPivot-- > 0; ) if (resultSet[iPivot] < resultSet[iPivot + 1] - 1) break;
if (iPivot < 0) yield break; // 4)
// 3) "regeneration"
var diff = resultSet[iPivot] + 1 - iPivot; // difference between pivotValue and its index
// fill resultSet after pivot with ascending sequence keeps it ordered without Repetitions
for (var i = iPivot; i <= ubound; i++) resultSet[i] = i + diff;
} while (true);
case CombinatoricMode.Combination_WithRepetitions: // keeps the resultSet asc-ordered
resultSet = Enumerable.Repeat(0, chooseK).ToArray(); // init resultSet with 0
do {
for (var n = resultSet[ubound]; n <= nMax; n++) { // 1) output-loop: enumerate last digit and yield results
resultSet[ubound] = n;
yield return resultSet.ToArray();
}
// find incrementable position
for (iPivot = ubound; iPivot-- > 0; ) if (resultSet[iPivot] < resultSet[iPivot + 1]) break;
if (iPivot < 0) yield break;
var pivotValue = resultSet[iPivot] + 1;
// fill resultSet after pivot with same pivotValue keeps it ordered with Repetitions
for (var i = iPivot; i <= ubound; i++) resultSet[i] = pivotValue;
} while (true);
case CombinatoricMode.Variation_WithRepetitions:
resultSet = Enumerable.Repeat(0, chooseK).ToArray();
do {
for (var n = resultSet[ubound]; n <= nMax; n++) { // 1) output-loop: enumerate last digit and yield results
resultSet[ubound] = n;
yield return resultSet.ToArray();
}
for (iPivot = chooseK; iPivot-- > 0; ) { // find incrementable position, set others to 0
if (resultSet[iPivot] < nMax) break;
else resultSet[iPivot] = 0;
}
if (iPivot < 0) yield break;
resultSet[iPivot] += 1;
} while (true);
case CombinatoricMode.Variation_NoRepetition:
// this is different, and results are not in lexicographic order
// to each Combination_NoRepetition-result the Permutation-algo is applied
// (Variation_WithRepetitions could be implemented analogously, but its actual Algo is faster, and ordered)
foreach (var result in ChooseKfromN(chooseK, fromN, CombinatoricMode.Combination_NoRepetition)) {
foreach (var perm in Permutation(result)) yield return perm;
}
break;
}
}
private string Preambel(int chooseK, int fromN, CombinatoricMode mode)
{
var sElementSet = string.Concat(Enumerable.Range(0, fromN));
return(string.Format("CombinatoricMode.{0}\nchoose {1} from {2} {{{3}}}\n", mode, chooseK, fromN, sElementSet));
}
