public SecretSantaDraw MakeNextDraw(List<Person> people, List<SecretSantaDraw> previousDraws)
{
//Only adults are included
string[] AllNames = GetNamesOfAdults(people);
List<Person> AllPeople = GetAdults(people);
Solver solver = new Solver("XmasDraw");
int n = AllNames.Count();
IEnumerable<int> RANGE = Enumerable.Range(0, n);
//
// Decision variables
//
IntVar[] santas = solver.MakeIntVarArray(n, 0, n - 1, "santas");
//
// Constraints
//
solver.Add(santas.AllDifferent());
foreach (int i in RANGE)
{
string currentPerson = AllNames[i];
//Can't buy for yourself
solver.Add(santas[i] != i);
//Can't buy for people in same family group
foreach (string familyMember in GetFamilyGroupMembers(currentPerson, AllPeople))
{
solver.Add(CantBuyFor(currentPerson, familyMember, AllNames, santas));
}
//Constraints based on history
foreach (SecretSantaDraw previousDraw in previousDraws)
{
if (previousDraw.Draw.ContainsKey(currentPerson))
{
string previousRecipient = previousDraw.Draw[currentPerson];
//Can't buy for who you previously bought for
solver.Add(CantBuyFor(currentPerson, previousRecipient, AllNames, santas));
//Your partner(s) can't buy for previousRecipient
foreach (string partner in GetImmediateFamilyMembers(currentPerson, AllPeople))
{
solver.Add(CantBuyFor(partner, previousRecipient, AllNames, santas));
}
//Can't buy for previousRecipient's partner(s)
foreach (string partner in GetImmediateFamilyMembers(previousRecipient, AllPeople))
{
solver.Add(CantBuyFor(currentPerson, partner, AllNames, santas));
}
}
}
//Constraints based on potential solutions
//TODO - Partners don't buy for other partners
}
solver.Add(solver.MakeCircuit(santas));
////Custom constraints
//solver.Add(CantBuyFor("Homer", "Fred", AllNames, santas));
//solver.Add(CantBuyFor("Homer", "Peter", AllNames, santas));
//solver.Add(CantBuyFor("Peter", "Homer", AllNames, santas));
//solver.Add(CantBuyFor("Peter", "Fred", AllNames, santas));
//solver.Add(CantBuyFor("Fred", "Homer", AllNames, santas));
//solver.Add(CantBuyFor("Fred", "Peter", AllNames, santas));
//
// Search
//
DecisionBuilder db = solver.MakePhase(santas,
Solver.INT_VAR_SIMPLE,
Solver.INT_VALUE_SIMPLE);
solver.NewSearch(db);
if (solver.NextSolution())
{
Dictionary<string, string> result = new Dictionary<string, string>();
foreach (int i in RANGE)
{
result[AllNames[i]] = AllNames[santas[i].Value()];
}
return new SecretSantaDraw("Result:" + DateTime.Now.Ticks, result);
}
else
{
return null;
}
}