private static void CombinationUtil(IReadOnlyList <int> arr, List <List <int> >[] combinationList, int [] data,
int start, int end,
int index, int r, int pos, List <int> auxList, int[,] matrix)
{
List <int> auxList2 = new List <int>();
// Current combination is
// ready to be printed,
// print it
if (index == r)
{
for (int j = 0; j < r; j++)
{
auxList2.Add(data[j]);
}
var auxMatrix = CreateAuxMatrix(matrix, auxList2, pos);
if (GridFiller.LineDone(auxMatrix, 0, pos, FileManager.rowList[pos]))
{
combinationList[pos].Add(auxList2);
}
return;
}
// replace index with all
// possible elements. The
// condition "end-i+1 >=
// r-index" makes sure that
// including one element
// at index will make a
// combination with remaining
// elements at remaining positions
for (int i = start; i <= end &&
end - i + 1 >= r - index; i++)
{
data[index] = arr[i];
CombinationUtil(arr, combinationList, data, i + 1,
end, index + 1, r, pos, auxList, matrix);
}
}