/// <summary>
/// Tries all 3Opt Moves for the neighbourhood of v1.
/// </summary>
/// <returns></returns>
public bool Try3OptMoves(TSProblem problem, float[][] weights, Tour tour, int v1, out float delta)
{
// get v_2.
var v2 = tour.GetNeigbour(v1);
if (v2 < 0)
{
delta = 0;
return(false);
}
var betweenV2V1 = tour.Between(v2, v1);
//var weightV1V2 = weights[v1][v2];
var weightV1V2 = weights.WeightWithoutTurns(v1, v2);
if (DirectedHelper.ExtractId(v2) == problem.First && !problem.Last.HasValue)
{ // set to zero if not closed.
weightV1V2 = 0;
}
int v3 = -1;
NearestNeighbours neighbours = null;
if (_nearestNeighbours)
{
neighbours = problem.GetNNearestNeighboursForward(10, DirectedHelper.ExtractId(v1));
}
foreach (int v4 in betweenV2V1)
{
if (v3 >= 0 && v3 != v1)
{
var v4Id = DirectedHelper.ExtractId(v4);
if (!_nearestNeighbours ||
neighbours.Contains(v4Id))
{
//var weightV1V4 = weights[v1][v4];
var weightV1V4 = weights.WeightWithoutTurns(v1, v4);
//var weightV3V4 = weights[v3][v4];
var weightV3V4 = weights.WeightWithoutTurns(v3, v4);
if (v4Id == problem.First && !problem.Last.HasValue)
{ // set to zero if not closed.
weightV1V4 = 0;
weightV3V4 = 0;
}
var weightV1V2PlusV3V4 = weightV1V2 + weightV3V4;
//var weightsV3 = weights[v3];
var weightsV3 = weights[DirectedHelper.ExtractDepartureId(v3)];
if (this.Try3OptMoves(problem, weights, tour, v1, v2, v3, weightsV3, v4, weightV1V2PlusV3V4, weightV1V4, out delta))
{
return(true);
}
}
}
v3 = v4;
}
delta = 0;
return(false);
}
/// <summary>
/// Generate the nearest neighbour list.
/// </summary>
/// <returns></returns>
public NearestNeighbours GetNNearestNeighboursBackward(int n, int id)
{
if (_backwardNearestNeighbours == null)
{ // not there yet, create.
_backwardNearestNeighbours = new Dictionary <int, NearestNeighbours[]>();
}
NearestNeighbours[] nearestNeighbours = null;
if (!_backwardNearestNeighbours.TryGetValue(n, out nearestNeighbours))
{ // not found for n, create.
nearestNeighbours = new NearestNeighbours[this.Times.Length];
_backwardNearestNeighbours.Add(n, nearestNeighbours);
}
var result = nearestNeighbours[id];
if (result == null)
{ // not found, calculate.
result = NearestNeighbours.BackwardDirected(this.Times, n, id);
nearestNeighbours[id] = result;
}
return(result);
}
/// <summary>
/// Generate the nearest neighbour list.
/// </summary>
/// <returns></returns>
public NearestNeighbours GetNNearestNeighboursForward(int n, int customer)
{
if (_forwardNearestNeighbours == null)
{ // not there yet, create.
_forwardNearestNeighbours = new Dictionary <int, NearestNeighbours[]>();
}
NearestNeighbours[] nearestNeighbours = null;
if (!_forwardNearestNeighbours.TryGetValue(n, out nearestNeighbours))
{ // not found for n, create.
nearestNeighbours = new NearestNeighbours[this.Weights.Length];
_forwardNearestNeighbours.Add(n, nearestNeighbours);
}
var result = nearestNeighbours[customer];
if (result == null)
{ // not found, calculate.
result = NearestNeighbours.Forward(this.Weights, n, customer);
nearestNeighbours[customer] = result;
}
return(result);
}