/// <summary>
/// Considers one customer for relocation.
/// </summary>
/// <param name="problem"></param>
/// <param name="route"></param>
/// <param name="previous"></param>
/// <param name="current"></param>
/// <param name="next"></param>
/// <param name="route_weight"></param>
/// <param name="max"></param>
/// <returns></returns>
private bool ConsiderCustomer(IProblemWeights problem, IRoute route, int previous, int current, int next, double route_weight, double max)
{
// calculate the removal gain of the customer.
double removal_gain = problem.WeightMatrix[previous][current] + problem.WeightMatrix[current][next]
- problem.WeightMatrix[previous][next];
if (removal_gain > 0.0001)
{
// try and place the customer in the next route.
CheapestInsertionResult result =
CheapestInsertionHelper.CalculateBestPlacement(problem, route, current);
if (result.Increase < removal_gain - 0.001 && route_weight + result.Increase < max)
{ // there is a gain in relocating this customer.
int count_before = route.Count;
// string route_string = route.ToString();
// and the route is still within bounds!
route.ReplaceEdgeFrom(result.CustomerBefore, result.Customer);
route.ReplaceEdgeFrom(result.Customer, result.CustomerAfter);
int count_after = route.Count;
if (count_before + 1 != count_after)
{
throw new Exception();
}
return(true);
}
}
return(false);
}
/// <summary>
/// Removes the edge from->unknown and replaces it with the edge from->to.
/// 0->1->2:ReplaceEdgeFrom(0, 2):0->2 without resetting the last customer property.
/// </summary>
/// <param name="from"></param>
/// <param name="to"></param>
public void ReplaceEdgeFrom(int from, int to)
{
if (to == 0 && from == 0)
{ // clear all elements from the route.
_route.Clear();
}
else if (to == 0)
{
_route.ReplaceEdgeFrom(from, -1);
}
else if (from == 0)
{ // TODO: replace the from customer.
_route.ReplaceFirst(to);
}
else
{
_route.ReplaceEdgeFrom(from, to);
}
}
/// <summary>
/// Tries a relocation of the customers in route1 to route2.
/// </summary>
/// <param name="problem"></param>
/// <param name="solution"></param>
/// <param name="route1_idx"></param>
/// <param name="route2_idx"></param>
/// <param name="max"></param>
/// <returns></returns>
private bool RelocateFromTo(MaxTimeProblem problem, MaxTimeSolution solution,
int route1_idx, int route2_idx, double max)
{
int previous = -1;
int current = -1;
IRoute route1 = solution.Route(route1_idx);
IRoute route2 = solution.Route(route2_idx);
double route2_weight = solution[route2_idx];
foreach (int next in route1)
{
if (previous >= 0 && current >= 0)
{ // consider the next customer.
int count_before1 = route1.Count;
int count_before2 = route2.Count;
// string route1_string = route1.ToString();
// string route2_string = route2.ToString();
if (this.ConsiderCustomer(problem, route2, previous, current, next, route2_weight, max))
{
route1.ReplaceEdgeFrom(previous, next);
int count_after = route1.Count + route2.Count;
if ((count_before1 + count_before2) != count_after)
{
throw new Exception();
}
return(true);
}
}
previous = current;
current = next;
}
return(false);
}
/// <summary>
/// Considers one customer for relocation.
/// </summary>
/// <param name="problem"></param>
/// <param name="route"></param>
/// <param name="previous"></param>
/// <param name="current"></param>
/// <param name="next"></param>
/// <param name="route_weight"></param>
/// <param name="max"></param>
/// <returns></returns>
private bool ConsiderCustomer(IProblemWeights problem, IRoute route, int previous, int current, int next, double route_weight, double max)
{
// calculate the removal gain of the customer.
double removal_gain = problem.WeightMatrix[previous][current] + problem.WeightMatrix[current][next]
- problem.WeightMatrix[previous][next];
if (removal_gain > 0.0001)
{
// try and place the customer in the next route.
CheapestInsertionResult result =
CheapestInsertionHelper.CalculateBestPlacement(problem, route, current);
if (result.Increase < removal_gain - 0.001 && route_weight + result.Increase < max)
{ // there is a gain in relocating this customer.
int count_before = route.Count;
// string route_string = route.ToString();
// and the route is still within bounds!
route.ReplaceEdgeFrom(result.CustomerBefore, result.Customer);
route.ReplaceEdgeFrom(result.Customer, result.CustomerAfter);
int count_after = route.Count;
if (count_before + 1 != count_after)
{
throw new Exception();
}
return true;
}
}
return false;
}
/// <summary>
/// Applies inter-improvements by exchanging customers.
/// </summary>
/// <param name="problem"></param>
/// <param name="solution"></param>
/// <param name="route1_idx"></param>
/// <param name="route2_idx"></param>
/// <param name="max"></param>
/// <returns></returns>
public bool Improve(MaxTimeProblem problem, MaxTimeSolution solution,
int route1_idx, int route2_idx, double max)
{
IRoute route1 = solution.Route(route1_idx);
IRoute route2 = solution.Route(route2_idx);
double total_before = problem.Time(solution.Route(route1_idx)) +
problem.Time(solution.Route(route2_idx));
double route1_size = solution[route1_idx];
double route2_size = solution[route2_idx];
// this heuristic removes a customer1 from route1 and a customer2 from route2 and inserts the customers again
// but swappes them; customer1 in route2 and customer2 in route1.
int previous_customer1 = -1;
//if (route1.IsRound)
//{
// previous_customer1= route1.Last; // set the previous customer.
//}
foreach (int customer1 in route1)
{ // loop over all customers in route1.
if (previous_customer1 >= 0)
{ // the previous customer is set.
int next_customer1 = route1.GetNeigbours(customer1)[0];
if (next_customer1 < 0)
{
continue;
}
int previous_customer2 = -1;
//if (route2.IsRound)
//{
// previous_customer2 = route2.Last; // set the previous customer.
//}
foreach (int customer2 in route2)
{ // loop over all customers in route2.
int next_customer2 = route2.GetNeigbours(customer2)[0];
if (previous_customer2 >= 0 && next_customer2 >= 0)
{ // the previous customer is set.
float weight1 = (float)problem.WeightMatrix[previous_customer1][customer1] +
(float)problem.WeightMatrix[customer1][next_customer1];
float weight2 = (float)problem.WeightMatrix[previous_customer2][customer2] +
(float)problem.WeightMatrix[customer2][next_customer2];
float weight1_after = (float)problem.WeightMatrix[previous_customer1][customer2] +
(float)problem.WeightMatrix[customer2][next_customer1];
float weight2_after = (float)problem.WeightMatrix[previous_customer2][customer1] +
(float)problem.WeightMatrix[customer1][next_customer2];
double difference = (weight1_after + weight2_after) - (weight1 + weight2);
if (difference < -0.01)
{ // the old weights are bigger!
// check if the new routes are bigger than max.
if (route1_size + (weight1_after - weight1) <= max &&
route2_size + (weight2_after - weight1) <= max)
{ // the exchange can happen, both routes stay within bound!
// exchange customer.
int count_before = route1.Count + route2.Count;
//route1.Remove(customer1);
//route2.Remove(customer2);
if (previous_customer1 == next_customer2)
{
throw new Exception();
}
//route1.InsertAfter(previous_customer1, customer2);
//route2.InsertAfter(previous_customer2, customer1);
route1.ReplaceEdgeFrom(previous_customer1, customer2);
route1.ReplaceEdgeFrom(customer2, next_customer1);
route2.ReplaceEdgeFrom(previous_customer2, customer1);
route2.ReplaceEdgeFrom(customer1, next_customer2);
int count_after = route1.Count + route2.Count;
if (count_before != count_after)
{
throw new Exception();
}
double total_after = problem.Time(solution.Route(route1_idx)) +
problem.Time(solution.Route(route2_idx));
if (total_after >= total_before)
{
throw new Exception("this is not an improvement!");
}
return(true);
}
}
}
previous_customer2 = customer2; // set the previous customer.
}
}
previous_customer1 = customer1; // set the previous customer.
}
return(false);
}
/// <summary>
/// Applies inter-improvements by exchanging parts of the route(s).
/// </summary>
/// <param name="problem"></param>
/// <param name="solution"></param>
/// <param name="route1_idx"></param>
/// <param name="route2_idx"></param>
/// <param name="max"></param>
/// <returns></returns>
public bool Improve(MaxTimeProblem problem, MaxTimeSolution solution,
int route1_idx, int route2_idx, double max)
{
int max_window = 40;
IRoute route1 = solution.Route(route1_idx);
IRoute route2 = solution.Route(route2_idx);
int route1_customers = route1.Count;
int route2_customers = route2.Count;
double[] route1_cumul = problem.TimeCumul(route1);
double[] route2_cumul = problem.TimeCumul(route2);
// build all edge weights.
List <Edge> route1_edges = new List <Edge>(route1.Edges());
List <Edge> route2_edges = new List <Edge>(route2.Edges());
double[] route1_weights = new double[route1_edges.Count];
for (int idx = 0; idx < route1_edges.Count; idx++)
{
Edge edge = route1_edges[idx];
route1_weights[idx] = problem.WeightMatrix[edge.From][edge.To];
}
double[] route2_weights = new double[route2_edges.Count];
for (int idx = 0; idx < route2_edges.Count; idx++)
{
Edge edge = route2_edges[idx];
route2_weights[idx] = problem.WeightMatrix[edge.From][edge.To];
}
List <EdgePair> route2_pairs = new List <EdgePair>();
for (int i_idx = 0; i_idx < route2_edges.Count - 2; i_idx++)
{
Edge i = route2_edges[i_idx];
double i_weight = route2_weights[i_idx];
double weight_before_i = route2_cumul[i_idx];
int k_idx_max = route2_edges.Count;
if (k_idx_max > i_idx + 2 + max_window)
{
k_idx_max = i_idx + 2 + max_window;
}
for (int k_idx = i_idx + 2; k_idx < k_idx_max; k_idx++)
{
Edge k = route2_edges[k_idx];
double k_weight = route2_weights[k_idx];
double weight_after_k = route2_cumul[route2_cumul.Length - 1] - route2_cumul[k_idx + 1];
double weight_between_route = route2_cumul[k_idx] - route2_cumul[i_idx + 1];
route2_pairs.Add(new EdgePair()
{
First = i,
FirstWeight = i_weight,
Second = k,
SecondWeight = k_weight,
Between = new List <int>(route2.Between(i.To, k.From)),
WeightTotal = i_weight + k_weight,
WeightAfter = weight_after_k,
WeightBefore = weight_before_i,
WeightBetween = weight_between_route,
CustomersBetween = k_idx - i_idx
});
}
}
// build all edge pairs.
for (int i_idx = 0; i_idx < route1_edges.Count - 2; i_idx++)
{
Edge i = route1_edges[i_idx];
double i_weight = route1_weights[i_idx];
double weight_before_i = route1_cumul[i_idx];
int k_idx_max = route1_edges.Count;
if (k_idx_max > i_idx + 2 + max_window)
{
k_idx_max = i_idx + 2 + max_window;
}
for (int k_idx = i_idx + 2; k_idx < k_idx_max; k_idx++)
{
Edge k = route1_edges[k_idx];
double k_weight = route1_weights[k_idx];
double weight_after_k = route1_cumul[route1_cumul.Length - 1] - route1_cumul[k_idx + 1];
double weight_between_route = route1_cumul[k_idx] - route1_cumul[i_idx + 1];
EdgePair pair1 = new EdgePair()
{
First = i,
FirstWeight = i_weight,
Second = k,
SecondWeight = k_weight,
Between = new List <int>(route1.Between(i.To, k.From)),
WeightTotal = i_weight + k_weight,
WeightAfter = weight_after_k,
WeightBefore = weight_before_i,
WeightBetween = weight_between_route,
CustomersBetween = k_idx - i_idx
};
foreach (EdgePair pair2 in route2_pairs)
{
double existing_weight = pair1.WeightTotal + pair2.WeightTotal;
//double new_weight = 0;
// get first route new.
double new_weight = problem.WeightMatrix[pair1.First.From][pair2.First.To];
//new_weight = first_route1_new;
if (new_weight > existing_weight - 0.001)
{
continue;
}
double first_route2_new = problem.WeightMatrix[pair2.First.From][pair1.First.To];
new_weight = new_weight + first_route2_new;
if (new_weight > existing_weight - 0.001)
{
continue;
}
double second_route1_new = problem.WeightMatrix[pair1.Second.From][pair2.Second.To];
new_weight = new_weight + second_route1_new;
if (new_weight > existing_weight - 0.001)
{
continue;
}
double second_route2_new = problem.WeightMatrix[pair2.Second.From][pair1.Second.To];
new_weight = new_weight + second_route2_new;
if (new_weight < existing_weight - 0.001)
{ // there is a decrease in total weight; check bounds.
double route1_weight = pair1.WeightBefore + pair2.WeightBetween + pair1.WeightAfter;
double route2_weight = pair2.WeightBefore + pair1.WeightBetween + pair2.WeightAfter;
// calculate the maximum.
int route1_customers_between = pair1.CustomersBetween;
int route2_customers_between = pair1.CustomersBetween;
route1_weight = problem.Time(route1_weight,
route1_customers - route1_customers_between + route2_customers_between);
route2_weight = problem.Time(route2_weight,
route2_customers - route2_customers_between + route1_customers_between);
if (route1_weight < max && route2_weight < max)
{
MaxTimeSolution solution_copy = solution.Clone() as MaxTimeSolution;
List <int> route1_between = pair1.Between;
List <int> route2_between = pair2.Between;
route1.ReplaceEdgeFrom(pair1.First.From, pair1.Second.To);
route2.ReplaceEdgeFrom(pair2.First.From, pair2.Second.To);
int previous = pair1.First.From;
for (int idx = 0; idx < route2_between.Count; idx++)
{
route1.ReplaceEdgeFrom(previous, route2_between[idx]);
previous = route2_between[idx];
}
route1.ReplaceEdgeFrom(previous, pair1.Second.To);
previous = pair2.First.From;
for (int idx = 0; idx < route1_between.Count; idx++)
{
route2.ReplaceEdgeFrom(previous, route1_between[idx]);
previous = route1_between[idx];
}
route2.ReplaceEdgeFrom(previous, pair2.Second.To);
if (!solution.IsValid())
{
throw new Exception();
}
return(true);
}
}
}
}
}
return(false);
}
/// <summary>
/// Tries all 3Opt Moves for the neighbourhood of v_1 containing v_3.
/// </summary>
/// <param name="problem"></param>
/// <param name="weights"></param>
/// <param name="route"></param>
/// <param name="v1"></param>
/// <param name="v_2"></param>
/// <param name="v_3"></param>
/// <param name="weights_3"></param>
/// <param name="v_4"></param>
/// <param name="weight_1_2_plus_3_4"></param>
/// <param name="weight_1_4"></param>
/// <returns></returns>
public bool Try3OptMoves(IProblemWeights problem, double[][] weights, IRoute route,
int v1, int v_2, int v_3, double[] weights_3, int v_4, double weight_1_2_plus_3_4, double weight_1_4)
{
//IEnumerable<int> between_v_4_v_1 = route.Between(v_4, v_1);
//foreach (int v_5 in between_v_4_v_1)
//{
// if (v_5 != v_1)
// {
// if (this.Try3OptMove(problem, weights, route, v_1, v_2, v_3, weights_3, v_4, weight_1_2_plus_3_4, weight_1_4, v_5))
// {
// return true;
// }
// }
//}
//return false;
IEnumerator <int> between_v_4_v_1_enumerator = route.Between(v_4, v1).GetEnumerator();
if (between_v_4_v_1_enumerator.MoveNext())
{
int v_5 = between_v_4_v_1_enumerator.Current;
if (v_5 != v1)
{
while (between_v_4_v_1_enumerator.MoveNext())
{
int v_6 = between_v_4_v_1_enumerator.Current;
//Console.WriteLine(v_6);
//if (this.Try3OptMove(problem, weights,
// route, v_1, v_2, v_3, weights_3, v_4,
// weight_1_2_plus_3_4, weight_1_4, v_5, v_6))
//{
// calculate the total weight of the 'new' arcs.
double weight_new = weight_1_4 +
weights_3[v_6] +
weights[v_5][v_2];
// calculate the total weights.
double weight = weight_1_2_plus_3_4 + weights[v_5][v_6];
if (weight - weight_new > _epsilon)
{ // actually do replace the vertices.
int count_before = route.Count;
//string route_string = route.ToString();
route.ReplaceEdgeFrom(v1, v_4);
route.ReplaceEdgeFrom(v_3, v_6);
route.ReplaceEdgeFrom(v_5, v_2);
int count_after = route.Count;
if (count_before != count_after)
{
throw new Exception();
}
// set bits.
//this.Set(problem, v_1, false);
this.Set(problem, v_3, false);
this.Set(problem, v_5, false);
if (!route.IsValid())
{
throw new Exception();
}
return(true); // move succeeded.
}
//}
v_5 = v_6;
}
}
}
return(false);
}
/// <summary>
/// Tries to relocate customers using the source the same as the CrossExchange but places customers using cheapest insertion.
/// </summary>
/// <param name="problem"></param>
/// <param name="solution"></param>
/// <param name="route1_idx"></param>
/// <param name="route2_idx"></param>
/// <param name="max"></param>
/// <returns></returns>
public bool Improve(MaxTimeProblem problem, MaxTimeSolution solution,
int route1_idx, int route2_idx, double max)
{
int max_window = 10;
IRoute route1 = solution.Route(route1_idx);
IRoute route2 = solution.Route(route2_idx);
double total_before = problem.Time(solution.Route(route1_idx)) +
problem.Time(solution.Route(route2_idx));
int route1_customers = route1.Count;
int route2_customers = route2.Count;
double[] route1_cumul = problem.TimeCumul(route1);
double[] route2_cumul = problem.TimeCumul(route2);
// build all edge weights.
List <Edge> route1_edges = new List <Edge>(route1.Edges());
List <Edge> route2_edges = new List <Edge>(route2.Edges());
double[] route1_weights = new double[route1_edges.Count];
for (int idx = 0; idx < route1_edges.Count; idx++)
{
Edge edge = route1_edges[idx];
route1_weights[idx] = problem.WeightMatrix[edge.From][edge.To];
}
double[] route2_weights = new double[route2_edges.Count];
for (int idx = 0; idx < route2_edges.Count; idx++)
{
Edge edge = route2_edges[idx];
route2_weights[idx] = problem.WeightMatrix[edge.From][edge.To];
}
List <EdgePair> route2_pairs = new List <EdgePair>();
for (int i_idx = 0; i_idx < route2_edges.Count - 2; i_idx++)
{
Edge i = route2_edges[i_idx];
double i_weight = route2_weights[i_idx];
double weight_before_i = route2_cumul[i_idx];
int k_idx_max = route2_edges.Count;
if (k_idx_max > i_idx + 2 + max_window)
{
k_idx_max = i_idx + 2 + max_window;
}
for (int k_idx = i_idx + 2; k_idx < k_idx_max; k_idx++)
{
Edge k = route2_edges[k_idx];
double k_weight = route2_weights[k_idx];
double weight_after_k = route2_cumul[route2_cumul.Length - 1] - route2_cumul[k_idx + 1];
double weight_between_route = route2_cumul[k_idx] - route2_cumul[i_idx + 1];
route2_pairs.Add(new EdgePair()
{
First = i,
FirstWeight = i_weight,
Second = k,
SecondWeight = k_weight,
Between = new List <int>(route2.Between(i.To, k.From)),
WeightTotal = i_weight + k_weight,
WeightAfter = weight_after_k,
WeightBefore = weight_before_i,
WeightBetween = weight_between_route,
CustomersBetween = k_idx - i_idx
});
}
}
// try to relocate all and find best pair.
double route1_weight = route1_cumul[route1_cumul.Length - 1];
EdgePair best = null;
CheapestInsertionResult best_result = new CheapestInsertionResult();
double best_extra = double.MaxValue;
foreach (EdgePair pair2 in route2_pairs)
{
// calculate cheapest insertion.
CheapestInsertionResult result =
CheapestInsertionHelper.CalculateBestPlacement(problem, route1,
pair2.First.To, pair2.Second.From);
double extra_route2 = problem.WeightMatrix[pair2.First.From][pair2.Second.To];
// check if the result has a net-decrease.
if (result.Increase + extra_route2 < pair2.WeightTotal - 0.01)
{ // there is a net decrease.
// calculate the real increase.
double new_weight = problem.Time(route1_weight + result.Increase + pair2.WeightBetween, route1_customers +
pair2.CustomersBetween);
// check the max.
if (new_weight < max && new_weight < best_extra)
{ // the route is smaller than max.
best_extra = new_weight;
best_result = result;
best = pair2;
}
}
}
if (best != null)
{
if (route2.Last == best.Second.To)
{
//throw new Exception();
}
route2.ReplaceEdgeFrom(best.First.From, best.Second.To);
int previous = best_result.CustomerBefore;
foreach (int customer in best.Between)
{
route1.ReplaceEdgeFrom(previous, customer);
previous = customer;
}
route1.ReplaceEdgeFrom(previous, best_result.CustomerAfter);
// check validity.
if (!route2.IsValid())
{
throw new Exception();
}
if (!route1.IsValid())
{
throw new Exception();
}
if (route1.Count + route2.Count != route1_customers + route2_customers)
{
throw new Exception();
}
double total_after = problem.Time(solution.Route(route1_idx)) +
problem.Time(solution.Route(route2_idx));
if (total_after >= total_before)
{
throw new Exception("this is not an improvement!");
}
return(true);
}
return(false);
}
/// <summary>
/// Tries all 3Opt Moves for the neighbourhood of v_1 containing v_3.
/// </summary>
/// <param name="problem"></param>
/// <param name="weights"></param>
/// <param name="route"></param>
/// <param name="v1"></param>
/// <param name="v_2"></param>
/// <param name="v_3"></param>
/// <param name="weights_3"></param>
/// <param name="v_4"></param>
/// <param name="weight_1_2_plus_3_4"></param>
/// <param name="weight_1_4"></param>
/// <returns></returns>
public bool Try3OptMoves(IProblemWeights problem, double[][] weights, IRoute route,
int v1, int v_2, int v_3, double[] weights_3, int v_4, double weight_1_2_plus_3_4, double weight_1_4)
{
//IEnumerable<int> between_v_4_v_1 = route.Between(v_4, v_1);
//foreach (int v_5 in between_v_4_v_1)
//{
// if (v_5 != v_1)
// {
// if (this.Try3OptMove(problem, weights, route, v_1, v_2, v_3, weights_3, v_4, weight_1_2_plus_3_4, weight_1_4, v_5))
// {
// return true;
// }
// }
//}
//return false;
IEnumerator<int> between_v_4_v_1_enumerator = route.Between(v_4, v1).GetEnumerator();
if (between_v_4_v_1_enumerator.MoveNext())
{
int v_5 = between_v_4_v_1_enumerator.Current;
if (v_5 != v1)
{
while (between_v_4_v_1_enumerator.MoveNext())
{
int v_6 = between_v_4_v_1_enumerator.Current;
//Console.WriteLine(v_6);
//if (this.Try3OptMove(problem, weights,
// route, v_1, v_2, v_3, weights_3, v_4,
// weight_1_2_plus_3_4, weight_1_4, v_5, v_6))
//{
// calculate the total weight of the 'new' arcs.
double weight_new = weight_1_4 +
weights_3[v_6] +
weights[v_5][v_2];
// calculate the total weights.
double weight = weight_1_2_plus_3_4 + weights[v_5][v_6];
if (weight - weight_new > _epsilon)
{ // actually do replace the vertices.
int count_before = route.Count;
//string route_string = route.ToString();
route.ReplaceEdgeFrom(v1, v_4);
route.ReplaceEdgeFrom(v_3, v_6);
route.ReplaceEdgeFrom(v_5, v_2);
int count_after = route.Count;
if (count_before != count_after)
{
throw new Exception();
}
// set bits.
//this.Set(problem, v_1, false);
this.Set(problem, v_3, false);
this.Set(problem, v_5, false);
if (!route.IsValid())
{
throw new Exception();
}
return true; // move succeeded.
}
//}
v_5 = v_6;
}
}
}
return false;
}
/// <summary>
/// Calculates a solution.
/// </summary>
/// <param name="problem"></param>
/// <returns></returns>
internal override MaxTimeSolution Solve(MaxTimeProblem problem)
{
// create the calculator.
MaxTimeCalculator calculator = new MaxTimeCalculator(problem);
// create the solution.
MaxTimeSolution solution = new MaxTimeSolution(problem.Size, true);
double max = problem.Max.Value;
// keep placing customer until none are left.
List <int> customers = new List <int>(problem.Customers);
// create n routes.
for (int customer = 0; customer < customers.Count; customer++)
{
solution.Add(customer);
solution[solution.Count - 1] = calculator.CalculateOneRouteIncrease(
0, 0);
}
// creates a result.
MergeResult result = new MergeResult();
result.Weight = double.MaxValue;
// loop over all route pairs and merge the smallest merge.
while (result != null)
{ // keep looping until there is no result anymore.
result = new MergeResult();
result.Weight = double.MaxValue;
for (int route1_idx = 1; route1_idx < solution.Count; route1_idx++)
{ // keep looping over all routes.
for (int route2_idx = 0; route2_idx < solution.Count; route2_idx++)
{ // keep looping over all routes.
if (route1_idx == route2_idx)
{ // only consider different routes.
break;
}
// calculate the merge result.
MergeResult current_result = this.TryMerge(problem, solution,
route1_idx, route2_idx, problem.Max.Value);
// evaluate the current result.
if (current_result != null && current_result.Weight < result.Weight)
{ // current result is best.
result = current_result;
}
}
}
// evaluate the result.
if (result.Weight < double.MaxValue)
{ // there is a result; apply it!
IRoute source = solution.Route(result.RouteSourceId);
IRoute target = solution.Route(result.RouteTargetId);
//string source_string = source.ToString();
//string target_string = target.ToString();
if (target.Count > 1 && target.First == target.GetNeigbours(result.CustomerTargetSource)[0])
{
//throw new Exception();
}
// create an enumeration of all customers of source in the correct order.
IEnumerable <int> source_between = new List <int>(
source.Between(result.CustomerSourceSource, result.CustomerSourceTarget));
// insert after the complete source.
int previous = result.CustomerTargetSource;
int next = target.GetNeigbours(result.CustomerTargetSource)[0];
foreach (int source_customer in source_between)
{
// insert.
target.ReplaceEdgeFrom(previous, source_customer);
previous = source_customer; // update previous.
}
target.ReplaceEdgeFrom(previous, next);
// remove the source route.
solution.Remove(result.RouteSourceId);
solution.RemoveWeight(result.RouteTargetId);
// calculate the weight of the new route.
solution[result.RouteTargetId] = solution[result.RouteTargetId] + result.Weight +
solution[result.RouteSourceId];
if (!solution.IsValid())
{
throw new Exception();
}
}
else
{ // set the result null.
result = null;
}
}
return(solution);
}
public void TestDepotDynamicAsymmetricMultiRouteExchanges()
{
// create two routes.
// 0->11->12->13->14->15->0
// 0->21->22->23->24->25->0
var multiRoute = new MaxTimeSolution(0);
IRoute route1 = multiRoute.Add();
var customers = new List <int>(route1);
Assert.AreEqual(1, customers.Count);
Assert.AreEqual(0, customers[0]);
route1.InsertAfter(0, 11);
Assert.AreEqual("0->11", route1.ToString());
route1.InsertAfter(11, 12);
route1.InsertAfter(12, 13);
route1.InsertAfter(13, 14);
route1.InsertAfter(14, 15);
IRoute route2 = multiRoute.Add();
customers = new List <int>(route2);
Assert.AreEqual(1, customers.Count);
Assert.AreEqual(0, customers[0]);
route2.InsertAfter(0, 21);
Assert.AreEqual("0->21", route2.ToString());
route2.InsertAfter(21, 22);
route2.InsertAfter(22, 23);
route2.InsertAfter(23, 24);
route2.InsertAfter(24, 25);
customers = new List <int>(route1);
Assert.AreEqual(6, customers.Count);
Assert.AreEqual(0, customers[0]);
Assert.AreEqual(11, customers[1]);
Assert.AreEqual(12, customers[2]);
Assert.AreEqual(13, customers[3]);
Assert.AreEqual(14, customers[4]);
Assert.AreEqual(15, customers[5]);
customers = new List <int>(route2);
Assert.AreEqual(6, customers.Count);
Assert.AreEqual(0, customers[0]);
Assert.AreEqual(21, customers[1]);
Assert.AreEqual(22, customers[2]);
Assert.AreEqual(23, customers[3]);
Assert.AreEqual(24, customers[4]);
Assert.AreEqual(25, customers[5]);
// replace the entire first route.
route1.ReplaceEdgeFrom(0, 0);
route2.ReplaceEdgeFrom(25, 11);
route2.ReplaceEdgeFrom(11, 12);
route2.ReplaceEdgeFrom(12, 13);
route2.ReplaceEdgeFrom(13, 14);
route2.ReplaceEdgeFrom(14, 15);
Assert.IsTrue(multiRoute.IsValid());
// create two routes.
// 0->11->12->13->14->15->0
// 0->21->22->23->24->25->0
multiRoute = new MaxTimeSolution(0);
route1 = multiRoute.Add();
customers = new List <int>(route1);
Assert.AreEqual(1, customers.Count);
Assert.AreEqual(0, customers[0]);
route1.InsertAfter(0, 11);
Assert.AreEqual("0->11", route1.ToString());
route1.InsertAfter(11, 12);
route1.InsertAfter(12, 13);
route1.InsertAfter(13, 14);
route1.InsertAfter(14, 15);
route2 = multiRoute.Add();
customers = new List <int>(route2);
Assert.AreEqual(1, customers.Count);
Assert.AreEqual(0, customers[0]);
route2.InsertAfter(0, 21);
Assert.AreEqual("0->21", route2.ToString());
route2.InsertAfter(21, 22);
route2.InsertAfter(22, 23);
route2.InsertAfter(23, 24);
route2.InsertAfter(24, 25);
// exchange parts.
var part1 = new List <int>(route1.Between(11, 13));
var part2 = new List <int>(route2.Between(23, 25));
route1.ReplaceEdgeFrom(0, 14);
route2.ReplaceEdgeFrom(22, 0);
int previous = 0;
for (int idx = 0; idx < part2.Count; idx++)
{
route1.ReplaceEdgeFrom(previous, part2[idx]);
previous = part2[idx];
}
route1.ReplaceEdgeFrom(previous, 14);
previous = 22;
for (int idx = 0; idx < part1.Count; idx++)
{
route2.ReplaceEdgeFrom(previous, part1[idx]);
previous = part1[idx];
}
route2.ReplaceEdgeFrom(previous, 0);
Assert.IsTrue(multiRoute.IsValid());
customers = new List <int>(route1);
Assert.AreEqual(6, customers.Count);
Assert.AreEqual(0, customers[0]);
Assert.AreEqual(23, customers[1]);
Assert.AreEqual(24, customers[2]);
Assert.AreEqual(25, customers[3]);
Assert.AreEqual(14, customers[4]);
Assert.AreEqual(15, customers[5]);
customers = new List <int>(route2);
Assert.AreEqual(6, customers.Count);
Assert.AreEqual(0, customers[0]);
Assert.AreEqual(21, customers[1]);
Assert.AreEqual(22, customers[2]);
Assert.AreEqual(11, customers[3]);
Assert.AreEqual(12, customers[4]);
Assert.AreEqual(13, customers[5]);
// create two routes.
// 0->11->12->13->14->15->0
// 0->21->22->23->24->25->0
multiRoute = new MaxTimeSolution(0);
route1 = multiRoute.Add();
customers = new List <int>(route1);
Assert.AreEqual(1, customers.Count);
Assert.AreEqual(0, customers[0]);
route1.InsertAfter(0, 11);
Assert.AreEqual("0->11", route1.ToString());
route1.InsertAfter(11, 12);
route1.InsertAfter(12, 13);
route1.InsertAfter(13, 14);
route1.InsertAfter(14, 15);
route2 = multiRoute.Add();
customers = new List <int>(route2);
Assert.AreEqual(1, customers.Count);
Assert.AreEqual(0, customers[0]);
route2.InsertAfter(0, 21);
Assert.AreEqual("0->21", route2.ToString());
route2.InsertAfter(21, 22);
route2.InsertAfter(22, 23);
route2.InsertAfter(23, 24);
route2.InsertAfter(24, 25);
route1.ReplaceEdgeFrom(12, 15);
route1.ReplaceEdgeFrom(14, 11);
route1.ReplaceEdgeFrom(0, 13);
customers = new List <int>(route1);
Assert.AreEqual(6, customers.Count);
Assert.AreEqual(0, customers[0]);
Assert.AreEqual(13, customers[1]);
Assert.AreEqual(14, customers[2]);
Assert.AreEqual(11, customers[3]);
Assert.AreEqual(12, customers[4]);
Assert.AreEqual(15, customers[5]);
route1.ToString();
}
