private Assignment recursiveBackTrackingSearch(Assignment anAssignment)
{
if (anAssignment.isComplete())
{
return anAssignment;
}
string variable = anAssignment.selectFirstUnassignedVariable();
ArrayList domainValues = defaultOrderDomainOf(variable);
for (int i = 0; i < domainValues.Count; i++)
{
Object value = domainValues[i];
if (constraints.isSatisfiedWith(anAssignment, variable, value))
{
anAssignment.setAssignment(variable, value);
Assignment result = recursiveBackTrackingSearch(anAssignment);
if (result != null)
{
return result;
}
anAssignment.remove(variable);
}
}
return null;//failure
}
public bool isSatisfiedWith(Assignment assignment, string variable,
Object value)
{
ArrayList variableNeighbors = (ArrayList) neighbors[variable];
for (int i = 0; i < variableNeighbors.Count; i++)
{
string neighbor = variableNeighbors[i].ToString();
if (assignment.hasAssignmentFor(neighbor))
{
string neighborColor = assignment.getAssignment(neighbor).ToString();
if (neighborColor.Equals(value))
{
return false;
}
}
}
return true;
}
public Assignment copy()
{
Assignment _copy = new Assignment();
for (int i = 0; i < variables.Count; i++)
{
_copy.variables.Add(variables[i]);
}
//Iterator iter = hash.keySet().iterator();
IEnumerator iter = hash.Keys.GetEnumerator();
while (iter.MoveNext())
{
Object key = iter.Current;
//copy.hash.put(key, hash.get(key));
_copy.hash.Add(key,hash[key]);
}
return _copy;
}
private bool passesUnique(string s1, string s2, Assignment a2)
{
if (a2.hasAssignmentFor(s1) && a2.hasAssignmentFor(s2))
if (a2.getAssignment(s1).Equals(a2.getAssignment(s2)))
return false;
return true;
}
/*
* returns false if the assignment has more than one of each class assigned to it
* (ie color, cigarette, drink, etc)
*/
private bool passesUniqueClass(string s1, string s2,string s3, string s4, string s5, Assignment assignment)
{
if (!passesUnique(s1,s2,assignment))return false;
if (!passesUnique(s1,s3,assignment))return false;
if (!passesUnique(s1,s4,assignment))return false;
if (!passesUnique(s1,s5,assignment))return false;
if (!passesUnique(s2,s3,assignment))return false;
if (!passesUnique(s2,s4,assignment))return false;
if (!passesUnique(s2,s5,assignment))return false;
if (!passesUnique(s3,s4,assignment))return false;
if (!passesUnique(s3,s5,assignment))return false;
if (!passesUnique(s4,s5,assignment))return false;
return true;
}
public bool isSatisfiedWith( Assignment assignment,
string variable,
Object value)
{
//Checking constraints
int intVal = int.Parse(value.ToString());
Assignment a2 = assignment.copy();
a2.setAssignment(variable, value);
//uniqueness constraints
//colours
if (!passesUniqueClass("blue","yellow","red","green","ivory",a2))return false;
//drinks
if (!passesUniqueClass("coffee","tea","milk","juice","water",a2))return false;
//nationality
if (!passesUniqueClass("norwegian","englishman","japanese","ukrainian","spaniard",a2))return false;
// pets
if (!passesUniqueClass("fox","horse","dog","snails","zebra",a2))return false;
// cigarettes
if (!passesUniqueClass("parliament","kools","lucky-strike","chesterfield","old-gold",a2))return false;
//14 constraints:
//1
if (a2.hasAssignmentFor("englishman") && a2.hasAssignmentFor("red"))
if (!a2.getAssignment("englishman").Equals(a2.getAssignment("red")))
return false;
//2
if (a2.hasAssignmentFor("spaniard") && a2.hasAssignmentFor("dog"))
if (!a2.getAssignment("spaniard").Equals(a2.getAssignment("dog")))
return false;
//3
if (a2.hasAssignmentFor("coffee") && a2.hasAssignmentFor("green"))
if (!a2.getAssignment("coffee").Equals(a2.getAssignment("green")))
return false;
//4
if (a2.hasAssignmentFor("ukrainian") && a2.hasAssignmentFor("tea"))
if (!a2.getAssignment("ukrainian").Equals(a2.getAssignment("tea")))
return false;
//5
if (a2.hasAssignmentFor("green") && a2.hasAssignmentFor("ivory"))
{
//green must be directly to the right of ivory
int intGreen = int.Parse(a2.getAssignment("green").ToString());
int intIvory = int.Parse(a2.getAssignment("ivory").ToString());
if ((intGreen - intIvory) != 1)
return false;
}
//6
if (a2.hasAssignmentFor("old-gold") && a2.hasAssignmentFor("snails"))
if (!a2.getAssignment("old-gold").Equals(a2.getAssignment("snails")))
return false;
//7
if (a2.hasAssignmentFor("kools") && a2.hasAssignmentFor("yellow"))
if (!a2.getAssignment("kools").Equals(a2.getAssignment("yellow")))
return false;
//8
if (a2.hasAssignmentFor("milk"))
{
int intMilk = int.Parse(a2.getAssignment("milk").ToString());
if (intMilk != 3)
return false;
}
//9
if (a2.hasAssignmentFor("norwegian"))
{
int intNorwegian = int.Parse(a2.getAssignment("norwegian").ToString());
if (intNorwegian != 1)
return false;
}
//10.
if (a2.hasAssignmentFor("chesterfield") && a2.hasAssignmentFor("fox"))
{
int int1 = int.Parse( a2.getAssignment("chesterfield").ToString());
int int2 = int.Parse(a2.getAssignment("fox").ToString());
if (System.Math.Abs(int1 - int2) != 1)
return false;
}
//11.
if (a2.hasAssignmentFor("kools") && a2.hasAssignmentFor("horse"))
{
int int1 = int.Parse((String) a2.getAssignment("kools").ToString());
int int2 = int.Parse((String) a2.getAssignment("horse").ToString());
if (System.Math.Abs(int1 - int2) != 1)
return false;
}
//12
if (a2.hasAssignmentFor("lucky-strike") && a2.hasAssignmentFor("juice"))
if (!a2.getAssignment("lucky-strike").Equals(a2.getAssignment("juice")))
return false;
//13.
if (a2.hasAssignmentFor("japanese") && a2.hasAssignmentFor("parliament"))
if (!a2.getAssignment("japanese").Equals(a2.getAssignment("parliament")))
return false;
//14.
if (a2.hasAssignmentFor("norwegian") && a2.hasAssignmentFor("blue"))
{
int int1 = int.Parse(a2.getAssignment("norwegian").ToString());
int int2 = int.Parse(a2.getAssignment("blue").ToString());
if (System.Math.Abs(int1 - int2) != 1)
return false;
}
return true;
}
private Assignment generateRandomAssignment()
{
ArrayList vars = new ArrayList();
for (int i = 0; i < variables.Count; i++)
{
vars.Add(variables[i]);
}
Assignment assignment = new Assignment(vars);
for (int i = 0; i < variables.Count; i++)
{
string variable = variables[i].ToString();
Object randomValue = Util.selectRandomlyFromList(domains
.getDomainOf(variable));
//System.out.println("in generate Assignment setting");
assignment.setAssignment(variable, randomValue);
}
return assignment;
}
