/// <summary>
/// Generate the nearest neighbour list.
/// </summary>
/// <param name="v"></param>
/// <returns></returns>
public NearestNeighbours10 Get10NearestNeighbours(int v)
{
if (_neighbours == null)
{
_neighbours = new NearestNeighbours10[this.Size];
}
NearestNeighbours10 result = _neighbours[v];
if (result == null)
{
SortedDictionary <double, List <int> > neighbours = new SortedDictionary <double, List <int> >();
for (int customer = 0; customer < this.Size; customer++)
{
if (customer != v)
{
double weight = this.WeightMatrix[v][customer];
List <int> customers = null;
if (!neighbours.TryGetValue(weight, out customers))
{
customers = new List <int>();
neighbours.Add(weight, customers);
}
customers.Add(customer);
}
}
result = new NearestNeighbours10();
foreach (KeyValuePair <double, List <int> > pair in neighbours)
{
foreach (int customer in pair.Value)
{
if (result.Count < 10)
{
if (result.Max < pair.Key)
{
result.Max = pair.Key;
}
result.Add(customer);
}
else
{
break;
}
}
}
_neighbours[v] = result;
}
return(result);
}
/// <summary>
/// Tries all 3Opt Moves for the neighbourhood of v_1.
/// </summary>
/// <param name="problem"></param>
/// <param name="weights"></param>
/// <param name="route"></param>
/// <param name="v1"></param>
/// <returns></returns>
public bool Try3OptMoves(IProblemWeights problem, double[][] weights, IRoute route, int v1)
{
// get v_2.
int v_2 = route.GetNeigbours(v1)[0];
if (v_2 < 0)
{
return(false);
}
IEnumerable <int> between_v_2_v_1 = route.Between(v_2, v1);
double weight_1_2 = weights[v1][v_2];
int v_3 = -1;
NearestNeighbours10 neighbours = null;
if (_nearest_neighbours)
{
neighbours = problem.Get10NearestNeighbours(v1);
}
foreach (int v_4 in between_v_2_v_1)
{
if (v_3 >= 0 && v_3 != v1)
{
//if (!_nearest_neighbours ||
// neighbours.Max <= weight_1_4)
if (!_nearest_neighbours ||
neighbours.Contains(v_4))
{
double weight_1_4 = weights[v1][v_4];
double weight_1_2_plus_3_4 = weight_1_2 + weights[v_3][v_4];
double[] weights_3 = weights[v_3];
if (this.Try3OptMoves(problem, weights, route, v1, v_2, v_3, weights_3, v_4, weight_1_2_plus_3_4, weight_1_4))
{
return(true);
}
}
}
v_3 = v_4;
}
return(false);
}
/// <summary>
/// Generate the nearest neighbour list.
/// </summary>
/// <param name="v"></param>
/// <returns></returns>
public NearestNeighbours10 Get10NearestNeighbours(int v)
{
if (_neighbours == null)
{
_neighbours = new NearestNeighbours10[this.Size];
}
NearestNeighbours10 result = _neighbours[v];
if (result == null)
{
SortedDictionary<double, List<int>> neighbours = new SortedDictionary<double, List<int>>();
for (int customer = 0; customer < this.Size; customer++)
{
if (customer != v)
{
double weight = this.WeightMatrix[v][customer];
List<int> customers = null;
if (!neighbours.TryGetValue(weight, out customers))
{
customers = new List<int>();
neighbours.Add(weight, customers);
}
customers.Add(customer);
}
}
result = new NearestNeighbours10();
foreach (KeyValuePair<double, List<int>> pair in neighbours)
{
foreach (int customer in pair.Value)
{
if (result.Count < 10)
{
if (result.Max < pair.Key)
{
result.Max = pair.Key;
}
result.Add(customer);
}
else
{
break;
}
}
}
_neighbours[v] = result;
}
return result;
}
