private void TaskOnCellValueChanged(int value, int row, int column)
{
// the variables are inserted in the list in order, so this should
// work as long as the way to insert them doesn't change
Variable <int> variable = csp.GetVariables().ElementAt(9 * row + column);
var result = (value != 0) ?
Solver.UpdateVariable(csp, initial_assignment, variable, value) :
Solver.RemoveVariable(csp, initial_assignment, variable, new Domain <int>(1, 2, 3, 4, 5, 6, 7, 8, 9));
}
private async Task <Assignment <Tval> > Backtrack(ConstraintSatisfactionProblem <Tval> csp, Assignment <Tval> assignment)
{
if (assignment.IsComplete(csp.GetVariables()))
{
return(assignment);
}
Variable <Tval> variable = variableSelectionStrategy.SelectUnassignedVariable(csp, assignment);
foreach (Tval value in domainValueSelectionStragety.getOrderedDomainValues(variable, assignment, csp))
{
assignment.Assign(variable, value);
OnVariableAssigned(variable, value);
InferenceResults <Tval> inference = new InferenceResults <Tval>();
inference.StoreDomainForVariable(variable, variable.GetDomain());
variable.UpdateDomain(new Domain <Tval>(value));
// it should already be consistent if it reached this point
// since we make a pre-solving inference
//bool isConsistent = assignment.IsConsistent(csp.GetAllDiffConstraints());
//if (isConsistent)
if (true)
{
inference = await inferenceStrategy.Infer(csp, variable, value, inference);
if (inference.IsAssignmentConsistent())
{
Assignment <Tval> result = await Backtrack(csp, assignment);
if (result != null)
{
return(result);
}
}
}
assignment.RemoveAssignment(variable);
OnAssignmentRemoved(variable, value);
inference.RestoreOldDomains();
}
return(null);
}
public override Variable <Tval> SelectUnassignedVariable(ConstraintSatisfactionProblem <Tval> csp, Assignment <Tval> assignment)
{
HashSet <Variable <Tval> > unassigned_variables = new HashSet <Variable <Tval> >(csp.GetVariables());
unassigned_variables.ExceptWith(assignment.GetAssignedVariables());
Variable <Tval> variable = unassigned_variables.First();
foreach (Variable <Tval> v in unassigned_variables)
{
variable = (variable.GetDomain().Size() < v.GetDomain().Size()) ? variable : v;
}
return(variable);
}