/// <summary>
/// Applies this operator.
/// </summary>
public bool Apply(TSPTWProblem problem, TSPTWObjective objective, Tour solution, out float delta)
{
foreach (var c in solution.Triples())
{
int betterDirectedId;
bool switchDepartureId, switchedArrivalId;
if (DirectedHelper.SwitchToBestTurn(c.Along, c.From, c.To, problem.Times, problem.TurnPenalties, out betterDirectedId,
out switchDepartureId, out switchedArrivalId, out delta))
{ // an improvement was found.
solution.Replace(c.Along, betterDirectedId);
if (switchDepartureId)
{
var newFromId = DirectedHelper.SwitchDepartureOffset(c.From);
solution.Replace(c.From, newFromId);
}
if (switchedArrivalId)
{
var newToId = DirectedHelper.SwitchArrivalOffset(c.To);
solution.Replace(c.To, newToId);
}
return(true);
}
}
delta = 0;
return(false);
}
/// <summary>
/// Optimizes the given part of the tour by choosing the best improvements in either the departureOffset or arrivalOffset of the first/last customers or the turns at any of the intermediate ones.
/// </summary>
private float OptimizePart(TSPTWProblem problem, List <int> part)
{
int turn1, arrivalId1, departureId1, id1;
int turn2, arrivalId2, departureId2, id2;
int turn3, arrivalId3, departureId3, id3;
var delta = 0f; // the positive difference.
var arrivalIdChange = -1;
var departureIdChange = -1;
var customerIdx = -1;
var customerTurn = -1;
// try changing the departureId.
DirectedHelper.ExtractAll(part[0], out arrivalId1, out departureId1, out id1, out turn1);
DirectedHelper.ExtractAll(part[1], out arrivalId2, out departureId2, out id2, out turn2);
var weight = problem.TurnPenalties[turn1];
weight += problem.Times[departureId1][arrivalId2];
var new0 = DirectedHelper.SwitchDepartureOffset(part[0]);
DirectedHelper.ExtractAll(new0, out arrivalId3, out departureId3, out id3, out turn3);
var newWeight = problem.TurnPenalties[turn3];
newWeight += problem.Times[departureId3][arrivalId2];
if (newWeight < weight)
{ // there was an improvement found in changing the departure id.
departureIdChange = DirectedHelper.ExtractDepartureId(new0);
delta = newWeight - weight;
}
// try changing the arrivalId.
DirectedHelper.ExtractAll(part[part.Count - 2], out arrivalId1, out departureId1, out id1, out turn1);
DirectedHelper.ExtractAll(part[part.Count - 1], out arrivalId2, out departureId2, out id2, out turn2);
weight = problem.TurnPenalties[turn2];
weight += problem.Times[departureId1][arrivalId2];
var newLast = DirectedHelper.SwitchArrivalOffset(part[part.Count - 1]);
DirectedHelper.ExtractAll(newLast, out arrivalId3, out departureId3, out id3, out turn3);
newWeight = problem.TurnPenalties[turn3];
newWeight += problem.Times[departureId1][arrivalId3];
if (newWeight < weight &&
delta < (newWeight - weight))
{ // there was an improvement found in changing the arrival id.
arrivalIdChange = DirectedHelper.ExtractDepartureId(newLast);
departureIdChange = -1;
delta = newWeight - weight;
}
for (var c = 1; c < part.Count - 1; c++)
{
var perviousDepartureId = DirectedHelper.ExtractDepartureId(part[c - 1]);
DirectedHelper.ExtractAll(part[c], out arrivalId1, out departureId1, out id1, out turn1);
var nextArrivalid = DirectedHelper.ExtractArrivalId(part[c + 1]);
weight = problem.Times[perviousDepartureId][arrivalId1];
weight += problem.TurnPenalties[turn1];
weight += problem.Times[departureId1][nextArrivalid];
for (var t = 0; t < 3; t++)
{
if (t == turn1)
{
continue;
}
var newDirectedId = DirectedHelper.BuildDirectedId(id1, t);
DirectedHelper.ExtractAll(newDirectedId, out arrivalId2, out departureId2, out id2, out turn2);
newWeight = problem.Times[perviousDepartureId][arrivalId2];
newWeight += problem.TurnPenalties[turn2];
newWeight += problem.Times[departureId2][nextArrivalid];
if (newWeight < weight &&
delta < (newWeight - weight))
{ // there was an improvement found in changing the turn.
arrivalIdChange = -1;
departureIdChange = -1;
customerIdx = c;
customerTurn = t;
delta = newWeight - weight;
}
}
}
if (delta > 0)
{
if (departureIdChange != -1)
{
part[0] = DirectedHelper.SwitchDepartureOffset(part[0]);
}
else if (arrivalIdChange != -1)
{
part[part.Count - 1] = DirectedHelper.SwitchArrivalOffset(part[part.Count - 1]);
}
else if (customerIdx != -1)
{
part[customerIdx] = DirectedHelper.BuildDirectedId(
DirectedHelper.ExtractId(part[customerIdx]), customerTurn);
}
}
return(delta);
}
