//to do here: implement the methods we need
public static void TestAlgorithm()
{
// mock constraints
var constraints = new ConstraintsCollection();
constraints.Add(new MinimumFreeDaysConstraint(3));
constraints.Add(new ClashesConstraint(true));
// create courses
var i = 0;
var courses = AllCoursesData.TakeWhile(x => i++ < 6).ToList();
var scheduler = new Scheduler();
var allSolutions = scheduler.SolveSssp(courses, constraints);
Console.WriteLine(allSolutions.Count());
foreach (var solution in allSolutions)
{
solution.ExportToJson();
if (constraints.IsConsistent(solution, solution.First()) == false)
{
throw new Exception();
}
//PrintSolution(solution);
}
}
public double Rate(ConstraintsCollection constraints)
{
double timetableRate = 0;
foreach (var constraint in constraints)
{
timetableRate += constraint.RatePenalty * constraint.GetRateFactor(this);
}
return(Rating = timetableRate); // update Rating and return it
}
public void BacktrackingAllSolutions(List <ClassType> variables, Timetable instantiation, IPriorityQueue <Timetable> allSolutions, int index, ConstraintsCollection constraints, CancellationToken cancellationToken)
{
if (variables.Count == index)
{
// check constraints who can be calculated only after timetable is fully instantiated
if (!constraints.IsConsistent(instantiation, true))
{
return;
}
var rate = instantiation.Rate(constraints);
if (allSolutions.Count < 200)
{
allSolutions.Add(instantiation);
return;
}
if (rate < allSolutions.FindMax().Rating)
{
allSolutions.DeleteMax();
allSolutions.Add(instantiation);
}
return;
}
var variable = variables[index++];
var domain = variable.Groups;
foreach (var value in domain)
{
if (cancellationToken.IsCancellationRequested)
{
return;
}
var tempTimetable = instantiation.Copy();
tempTimetable.Add(value);
if (constraints.IsConsistent(tempTimetable, false))
{
BacktrackingAllSolutions(variables, tempTimetable, allSolutions, index, constraints, cancellationToken);
}
}
}
public IEnumerable <Timetable> SolveSssp(System.Collections.Generic.IList <Course> courses, ConstraintsCollection constraints)
{
var allClassTypes = GetAllClassTypes(courses);
var variables = ApplyMrvHeuristic(allClassTypes);
//allSolutions = MaxHeap
var backtrackingSolutions = new IntervalHeap <Timetable>(200);
// BT(Variables, {}, Domains, allSolutions)
var cancellationTokenSource = new CancellationTokenSource();
cancellationTokenSource.CancelAfter(TimeSpan.FromSeconds(20));
var cancellationToken = cancellationTokenSource.Token;
var backtrackingTask = Task.Factory.StartNew(
() =>
{
BacktrackingAllSolutions(variables, new Timetable(), backtrackingSolutions, 0, constraints, cancellationToken);
return(backtrackingSolutions);
}, cancellationToken);
// Generic algorithm
var geneticAlgorithmRunner = new TimetablerGeneticAlgorithmRunner(variables, constraints);
var geneticTask = geneticAlgorithmRunner.RunAsync();
Task.WaitAll(backtrackingTask);
var timetables = new List <Timetable>();
if (cancellationToken.IsCancellationRequested)
{
geneticTask.Wait();
timetables.Add(geneticAlgorithmRunner.GeneticSolution);
}
if (backtrackingSolutions.Any())
{
timetables.AddRange(backtrackingSolutions);
}
var sortedSolutions = SortByRate(timetables);
//Return allSolutions
return(sortedSolutions);
}
public TimetablerGeneticAlgorithmRunner(IList <ClassType> variables, ConstraintsCollection constraints)
{
Variables = variables;
Constraints = constraints;
}