/// <summary>
/// Combine all the IConstraints in only one IConstraint.
/// </summary>
/// <param name="expression">The expression, in the form of a list
/// of IConstraint in a postfix expression form</param>
/// <returns></returns>
public IConstraint ResolveExpression(IList <IConstraint> expression)
{
Stack <IConstraint> stack = new Stack <IConstraint>();
StringBuilder errors = new StringBuilder();
foreach (IConstraint IConstraint in expression)
{
if (IConstraint is BinaryConstraint)
{
BinaryConstraint binop = IConstraint as BinaryConstraint;
IConstraint right = stack.Pop();
IConstraint left = stack.Pop();
stack.Push(binop.SetConstraint(left, right));
}
else if (IConstraint is UnaryConstraint)
{
Debug.Assert(stack.Count > 0, "trying to apply an unary IConstraint on a null object");
UnaryConstraint unop = IConstraint as UnaryConstraint;
stack.Push(unop.SetConstraint(stack.Pop()));
}
else
{
stack.Push(IConstraint);
}
}
return(stack.Pop());
}
private Constraint GenerateBinaryNeighbor(int var1Id, int value1Id, int var2Id, int value2Id)
{
Constraint result = new BinaryConstraint <Permutation>()
{
Check = () => Variables[var1Id].Current == null || Variables[var2Id].Current == null ||
Math.Abs(Array.IndexOf(Variables[var1Id].Current.Values, value1Id) - Array.IndexOf(Variables[var2Id].Current.Values, value2Id)) == 1,
VariableA = Variables[var1Id],
VariableB = Variables[var2Id]
};
return(result);
}
public EinsteinCsp()
{
// setup variables
var yellow = new EinsteinVariable(EinsteinValue.Yellow, this);
var blue = new EinsteinVariable(EinsteinValue.Blue, this);
var red = new EinsteinVariable(EinsteinValue.Red, this);
var white = new EinsteinVariable(EinsteinValue.White, this);
var green = new EinsteinVariable(EinsteinValue.Green, this);
var norwegian = new EinsteinVariable(EinsteinValue.Norwegian, new List <House> {
House.First
}, this);
var dane = new EinsteinVariable(EinsteinValue.Dane, this);
var englishman = new EinsteinVariable(EinsteinValue.Englishman, this);
var german = new EinsteinVariable(EinsteinValue.German, this);
var swede = new EinsteinVariable(EinsteinValue.Swede, this);
var water = new EinsteinVariable(EinsteinValue.Water, this);
var tea = new EinsteinVariable(EinsteinValue.Tea, this);
var milk = new EinsteinVariable(EinsteinValue.Milk, new List <House> {
House.Third
}, this);
var beer = new EinsteinVariable(EinsteinValue.Beer, this);
var coffee = new EinsteinVariable(EinsteinValue.Coffee, this);
var cigar = new EinsteinVariable(EinsteinValue.Cigar, this);
var lights = new EinsteinVariable(EinsteinValue.Lights, this);
var noFilter = new EinsteinVariable(EinsteinValue.NoFilter, this);
var pipe = new EinsteinVariable(EinsteinValue.Pipe, this);
var menthol = new EinsteinVariable(EinsteinValue.Menthol, this);
var cat = new EinsteinVariable(EinsteinValue.Cat, this);
var horse = new EinsteinVariable(EinsteinValue.Horse, this);
var bird = new EinsteinVariable(EinsteinValue.Bird, this);
var dog = new EinsteinVariable(EinsteinValue.Dog, this);
var fish = new EinsteinVariable(EinsteinValue.Fish, this);
// setup riddle constraints
_ = new BinaryConstraint <EinsteinValue, House>[]
{
// riddle hints
new InTheSameHouse(englishman, red), //2nd
new InTheSameHouse(red, englishman),
new HouseOnTheLeft(white, green), //3rd
new HouseOnTheRight(green, white),
new InTheSameHouse(dane, tea), //4th
new InTheSameHouse(tea, dane),
new HouseNextTo(lights, cat), //5th
new HouseNextTo(cat, lights),
new InTheSameHouse(yellow, cigar), //6th
new InTheSameHouse(cigar, yellow),
new InTheSameHouse(german, pipe), //7th
new InTheSameHouse(pipe, german),
new HouseNextTo(lights, water), //9th
new HouseNextTo(water, lights),
new InTheSameHouse(noFilter, bird), //10th
new InTheSameHouse(bird, noFilter),
new InTheSameHouse(swede, dog), //11th
new InTheSameHouse(dog, swede),
new HouseNextTo(norwegian, blue), //12th
new HouseNextTo(blue, norwegian),
new HouseNextTo(horse, yellow), //13th
new HouseNextTo(yellow, horse),
new InTheSameHouse(menthol, beer), //14th
new InTheSameHouse(beer, menthol),
new InTheSameHouse(green, coffee), //15th
new InTheSameHouse(coffee, green)
};
// unique house constraints
var c = Constraints as List <BinaryConstraint <EinsteinValue, House> >;
// colors
foreach (var(bc1, bc2) in MathCsp.Combinations(yellow, blue, red, green, white)
.Select(pair =>
EinsteinBidirectionalConstraintFactory
.CreateBidirectionalConstraints(pair.Item1, pair.Item2, EinsteinConstraintType.UniqueHouse)))
{
c?.Add(bc1);
c?.Add(bc2);
}
// nationalities
foreach (var(bc1, bc2) in MathCsp.Combinations(german, norwegian, englishman, swede, dane)
.Select(pair =>
EinsteinBidirectionalConstraintFactory
.CreateBidirectionalConstraints(pair.Item1, pair.Item2, EinsteinConstraintType.UniqueHouse)))
{
c?.Add(bc1);
c?.Add(bc2);
}
// drinks
foreach (var(bc1, bc2) in MathCsp.Combinations(milk, water, beer, coffee, tea)
.Select(pair =>
EinsteinBidirectionalConstraintFactory
.CreateBidirectionalConstraints(pair.Item1, pair.Item2, EinsteinConstraintType.UniqueHouse)))
{
c?.Add(bc1);
c?.Add(bc2);
}
// pets
foreach (var(bc1, bc2) in MathCsp.Combinations(cat, dog, horse, fish, bird)
.Select(pair =>
EinsteinBidirectionalConstraintFactory
.CreateBidirectionalConstraints(pair.Item1, pair.Item2, EinsteinConstraintType.UniqueHouse)))
{
c?.Add(bc1);
c?.Add(bc2);
}
// smokes
foreach (var(bc1, bc2) in MathCsp.Combinations(noFilter, menthol, pipe, cigar, lights)
.Select(pair =>
EinsteinBidirectionalConstraintFactory
.CreateBidirectionalConstraints(pair.Item1, pair.Item2, EinsteinConstraintType.UniqueHouse)))
{
c?.Add(bc1);
c?.Add(bc2);
}
}