/// <summary>
///
/// </summary>
/// <param name="data"></param>
/// <param name="costCoefficient">way will be multiplied with this</param>
/// <param name="startCost">Additional cost from home to any visit</param>
public CostEvaluator(RoutingData data, int costCoefficient, int startCost)
{
timeEvaluator = new TimeEvaluator(data);
this.data = data;
this.costCoefficient = costCoefficient;
this.startCost = startCost;
}
/// <summary>
/// requires data.SantaIds
/// requires data.Visits
/// requires data.HomeIndex
/// requires data.Unavailable
/// requires data.Start
/// requires data.End
/// </summary>
public static OptimizationResult Solve(RoutingData data, long timeLimitMilliseconds, ITimeWindowStrategy strategy)
{
if (false ||
data.SantaIds == null ||
data.Visits == null ||
data.Unavailable == null ||
data.SantaStartIndex == null ||
data.SantaEndIndex == null
)
{
throw new ArgumentNullException();
}
var model = new RoutingModel(data.Visits.Length, data.SantaIds.Length, data.SantaStartIndex, data.SantaEndIndex);
// setting up dimensions
var maxTime = GetMaxTime(data);
var timeCallback = new TimeEvaluator(data);
model.AddDimension(timeCallback, 0, maxTime, false, DimensionTime);
var lengthCallback = new TimeEvaluator(data);
model.AddDimension(lengthCallback, 0, maxTime, true, DimensionLength);
// set additional cost of longest day
{
var dim = model.GetDimensionOrDie(DimensionLength);
dim.SetGlobalSpanCostCoefficient(data.Cost.CostLongestDayPerHour);
}
// dimensions for breaks
var breakCallbacks = new List <BreakEvaluator>();
var breakDimensions = new List <string>();
for (int santa = 0; santa < data.NumberOfSantas; santa++)
{
var maxBreaks = GetNumberOfBreaks(data, santa);
if (maxBreaks == 0)
{
// no breaks
continue;
}
var evaluator = new BreakEvaluator(data, santa);
var dimension = GetSantaBreakDimension(santa);
model.AddDimension(evaluator, 0, maxBreaks, true, dimension);
breakCallbacks.Add(evaluator);
breakDimensions.Add(dimension);
}
// setting up santas (=vehicles)
var costCallbacks = new NodeEvaluator2[data.NumberOfSantas];
for (int santa = 0; santa < data.NumberOfSantas; santa++)
{
// must be a new instance per santa
NodeEvaluator2 costCallback = data.Input.IsAdditionalSanta(data.SantaIds[santa])
? new CostEvaluator(data, data.Cost.CostWorkPerHour + data.Cost.CostAdditionalSantaPerHour, data.Cost.CostAdditionalSanta)
: new CostEvaluator(data, data.Cost.CostWorkPerHour, 0);
costCallbacks[santa] = costCallback;
model.SetVehicleCost(santa, costCallback);
// limit time per santa
var day = data.GetDayFromSanta(santa);
var start = GetDayStart(data, day);
var end = GetDayEnd(data, day);
model.CumulVar(model.End(santa), DimensionTime).SetRange(start, end);
model.CumulVar(model.Start(santa), DimensionTime).SetRange(start, end);
// avoid visiting breaks of other santas
var breakDimension = GetSantaBreakDimension(santa);
foreach (var dimension in breakDimensions.Except(new[] { breakDimension }))
{
model.CumulVar(model.End(santa), dimension).SetMax(0);
}
}
// setting up visits (=orders)
for (int visit = 0; visit < data.NumberOfVisits; ++visit)
{
var cumulTimeVar = model.CumulVar(visit, DimensionTime);
cumulTimeVar.SetRange(data.OverallStart, data.OverallEnd);
model.AddDisjunction(new[] { visit }, data.Cost.CostNotVisitedVisit);
// add desired / unavailable according to strategy
var timeDimension = model.GetDimensionOrDie(DimensionTime);
strategy.AddConstraints(data, model, cumulTimeVar, timeDimension, visit);
}
// Solving
var searchParameters = RoutingModel.DefaultSearchParameters();
searchParameters.FirstSolutionStrategy = FirstSolutionStrategy.Types.Value.Automatic; // maybe try AllUnperformed or PathCheapestArc
searchParameters.LocalSearchMetaheuristic = LocalSearchMetaheuristic.Types.Value.GuidedLocalSearch;
searchParameters.TimeLimitMs = timeLimitMilliseconds;
var solution = model.SolveWithParameters(searchParameters);
// protect callbacks from the GC
GC.KeepAlive(timeCallback);
GC.KeepAlive(lengthCallback);
foreach (var costCallback in costCallbacks)
{
GC.KeepAlive(costCallback);
}
foreach (var breakCallback in breakCallbacks)
{
GC.KeepAlive(breakCallback);
}
Debug.WriteLine($"obj={solution?.ObjectiveValue()}");
return(CreateResult(data, model, solution));
}