/// <summary>
/// Selects a new seed customer.
/// </summary>
/// <param name="problem"></param>
/// <param name="calculator"></param>
/// <param name="solution"></param>
/// <param name="customers"></param>
/// <returns></returns>
private int SelectSeed(MaxTimeProblem problem, MaxTimeCalculator calculator,
MaxTimeSolution solution, List <int> customers)
{
int selected_customer = -1;
double max_distance = double.MaxValue;
foreach (int customer_to_check in customers)
{
SortedDictionary <double, List <int> > neighbours = new SortedDictionary <double, List <int> >();
for (int idx = 0; idx < customers.Count; idx++)
{
int customer = customers[idx];
if (customer != customer_to_check)
{
double weight = problem.WeightMatrix[customer_to_check][customer] +
problem.WeightMatrix[customer_to_check][customer];
List <int> customers_list = null;
if (!neighbours.TryGetValue(weight, out customers_list))
{
customers_list = new List <int>();
neighbours.Add(weight, customers_list);
}
customers_list.Add(customer);
}
}
double nearest_neighbour_average = 0;
int neighbour_count = 20;
int neighbour_counted = 0;
foreach (KeyValuePair <double, List <int> > pair in neighbours)
{
foreach (int customer in pair.Value)
{
if (neighbour_counted < neighbour_count)
{
neighbour_counted++;
nearest_neighbour_average = nearest_neighbour_average +
pair.Key;
}
else
{
break;
}
}
}
if (max_distance > nearest_neighbour_average)
{
max_distance = nearest_neighbour_average;
selected_customer = customer_to_check;
}
}
return(selected_customer);
}
/// <summary>
/// Selects a new seed customer.
/// </summary>
/// <param name="problem"></param>
/// <param name="calculator"></param>
/// <param name="solution"></param>
/// <param name="customers"></param>
/// <returns></returns>
private int SelectSeed(MaxTimeProblem problem, MaxTimeCalculator calculator,
MaxTimeSolution solution, List <int> customers)
{ // select the customer farthest from the depot.
int selectedCustomer = -1;
double maxDistance = double.MinValue;
foreach (int customerToCheck in customers)
{
double distance = problem.WeightMatrix[0][customerToCheck] +
problem.WeightMatrix[customerToCheck][0];
if (distance > maxDistance)
{
maxDistance = distance;
selectedCustomer = customerToCheck;
}
}
return(selectedCustomer);
}
/// <summary>
/// Executes a solver procedure.
/// </summary>
/// <param name="problem"></param>
/// <returns></returns>
internal override MaxTimeSolution Solve(MaxTimeProblem problem)
{
MaxTimeCalculator calculator = new MaxTimeCalculator(problem);
// get the seed customers.
ICollection<int> seeds = _seed_selector.SelectSeeds(
problem, _k);
double[] weights = new double[seeds.Count];
// start the seed routes.
List<int> selectable_customers = problem.Customers;
MaxTimeSolution routes = new MaxTimeSolution(
problem.Size, true);
foreach (int seed in seeds)
{
routes.Add(seed);
selectable_customers.Remove(seed);
}
if (!routes.IsValid())
{
throw new Exception();
}
// keep a list of cheapest insertions.
IInsertionCosts costs = new BinaryHeapInsertionCosts();
// keep looping until all customers have been placed.
while (selectable_customers.Count > 0)
{
// try and place into every route.
CheapestInsertionResult best_result = new CheapestInsertionResult();
best_result.Increase = float.MaxValue;
int best_route_idx = -1;
CheapestInsertionResult best_result_above_max = new CheapestInsertionResult();
best_result_above_max.Increase = float.MaxValue;
int best_route_above_max_idx = -1;
for (int route_idx = 0; route_idx < routes.Count; route_idx++)
{
IRoute current_route = routes.Route(route_idx);
// choose the next customer.
CheapestInsertionResult result =
CheapestInsertionHelper.CalculateBestPlacement(problem, current_route, selectable_customers, costs);
if (result.Customer == result.CustomerAfter)
{
throw new Exception();
}
// get the current weight
double weight = weights[route_idx];
if (result.Increase < best_result.Increase)
{
if (weight + result.Increase + calculator.DeliveryTime < problem.Max.Value)
{ // route will still be inside bounds.
best_result = result;
best_route_idx = route_idx;
}
else
{ // route will become above max.
if (result.Increase < best_result_above_max.Increase)
{
best_result_above_max = result;
best_route_above_max_idx = route_idx;
}
}
}
}
// do the placement if a placement is found without max violation.
// else do the placement in the above max route.
CheapestInsertionResult placement_result = new CheapestInsertionResult();
placement_result.Increase = double.MaxValue;
int placement_result_idx = -1;
if (best_route_idx >= 0)
{ // best placement found.
placement_result = best_result;
placement_result_idx = best_route_idx;
}
else
{ // best placement found but only above max.
placement_result = best_result_above_max;
placement_result_idx = best_route_above_max_idx;
}
// do the actual placement.
weights[placement_result_idx] = calculator.CalculateOneRouteIncrease(
weights[placement_result_idx], placement_result.Increase);
selectable_customers.Remove(placement_result.Customer);
//routes.Route(placement_result_idx).InsertAfterAndRemove(
// placement_result.CustomerBefore, placement_result.Customer, placement_result.CustomerAfter);
routes.Route(placement_result_idx).InsertAfter(
placement_result.CustomerBefore, placement_result.Customer);
if (!routes.IsValid())
{
throw new Exception();
}
}
return routes;
}
/// <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 Individual <MaxTimeSolution, MaxTimeProblem, Fitness> CrossOver(
Solver <MaxTimeSolution, MaxTimeProblem, Fitness> solver,
Individual <MaxTimeSolution, MaxTimeProblem, Fitness> parent1,
Individual <MaxTimeSolution, MaxTimeProblem, Fitness> parent2)
{
MaxTimeCalculator calculator = new MaxTimeCalculator(solver.Problem);
MaxTimeSolution route1 = parent1.Genomes;
MaxTimeSolution route2 = parent2.Genomes;
// get the minimum size of both routes.
int size = route1.Count;
if (route2.Count < size)
{
size = route2.Count;
}
// select a random number of routes.
HashSet <int> selected_first = new HashSet <int>();
HashSet <int> selected_second = new HashSet <int>();
List <IRoute> selected_routes = new List <IRoute>();
bool first = true;
while (selected_routes.Count < size)
{
// select route.
int selected_route = -1;
if (first)
{
selected_route = this.ChooseNextFrom(selected_routes, route1, selected_first);
selected_first.Add(selected_route);
selected_routes.Add(route1.Route(selected_route));
}
else
{
selected_route = this.ChooseNextFrom(selected_routes, route2, selected_second);
selected_second.Add(selected_route);
selected_routes.Add(route2.Route(selected_route));
}
first = !first;
}
// generate the new customer genome.
MaxTimeSolution solution = new MaxTimeSolution(route1.Size, true);
int previous = -1;
foreach (IRoute route in selected_routes)
{
IRoute current_route = null;
foreach (int customer in route)
{
MaxTimeSolution copy = (solution.Clone() as MaxTimeSolution);
string solution_string = solution.ToString();
if (!solution.Contains(customer))
{
if (current_route == null)
{ // add the route.
current_route = solution.Add(customer);
// safe the previous customer.
previous = customer;
if (!solution.IsValid())
{
throw new Exception();
}
}
else
{ // add the customer.
string current_route_string = current_route.ToString();
//current_route.InsertAfterAndRemove(previous, customer, current_route.First);
current_route.InsertAfter(previous, customer);
//current_route.InsertAfter(customer, current_route.First);
if (!solution.IsValid())
{
throw new Exception();
}
// safe the previous customer.
previous = customer;
}
}
}
}
if (!solution.IsValid())
{
throw new Exception();
}
this.FillRoutes(calculator, route1, solution, solver.Problem);
if (!solution.IsValid())
{
throw new Exception();
}
return(new Individual <MaxTimeSolution, MaxTimeProblem, Fitness>(solution));
}
private void FillRoutes(MaxTimeCalculator calculator, MaxTimeSolution route1, MaxTimeSolution solution,
MaxTimeProblem problem)
{
double[] weights = new double[solution.Count];
// insert all non-placed customers in the order of the first route.
HashSet <int> unplaced = new HashSet <int>();
for (int route_idx = 0; route_idx < route1.Count; route_idx++)
{
IRoute route1_route = route1.Route(route_idx);
foreach (int customer in route1_route)
{
if (!solution.Contains(customer))
{
unplaced.Add(customer);
}
}
}
for (int idx = 0; idx < solution.Count; idx++)
{
IRoute route = solution.Route(idx);
weights[idx] = calculator.CalculateOneRoute(route);
}
// insert all non-placed customers in the order of the first route.
//for (int route_idx = 0; route_idx < route1.Count; route_idx++)
//{
// IRoute route1_route = route1.Route(route_idx);
// foreach (int customer in route1_route)
// {
// if (!solution.Contains(customer))
// {
while (unplaced.Count > 0)
{
int customer = unplaced.First <int>();
// try reinsertion.
CheapestInsertionResult result = new CheapestInsertionResult();
result.Increase = double.MaxValue;
int target_idx = -1;
CheapestInsertionResult unlimited_result = new CheapestInsertionResult();
unlimited_result.Increase = double.MaxValue;
int unlimited_target_idx = -1;
for (int idx = 0; idx < solution.Count; idx++)
{
IRoute route = solution.Route(idx);
CheapestInsertionResult current_result =
CheapestInsertionHelper.CalculateBestPlacement(problem.Weights, route, customer);
if (current_result.Increase < result.Increase)
{
if (weights[idx] + current_result.Increase < problem.Max.Value)
{
target_idx = idx;
result = current_result;
if (result.Increase <= 0)
{
break;
}
}
}
if (current_result.Increase < unlimited_result.Increase)
{
unlimited_target_idx = idx;
unlimited_result = current_result;
}
}
if (target_idx < 0)
{
result = unlimited_result;
target_idx = unlimited_target_idx;
}
// get the target route and insert.
IRoute target_route = solution.Route(target_idx);
weights[target_idx] = weights[target_idx] + result.Increase;
//target_route.InsertAfterAndRemove(result.CustomerBefore, result.Customer, result.CustomerAfter);
target_route.InsertAfter(result.CustomerBefore, result.Customer);
unplaced.Remove(result.Customer);
////solution.ToString();
//if (!solution.IsValid())
//{
// throw new Exception();
//}
}
// }
//}
}
internal override MaxTimeSolution Solve(MaxTimeProblem problem)
{
MaxTimeCalculator calculator = new MaxTimeCalculator(
problem);
// generate a ATSP solution.
IRoute tsp_solution = _tsp_solution;
if (tsp_solution == null)
{
tsp_solution = _tsp_solver.Solve(new TSPProblem(problem));
}
// generate subtours from this solution.
MaxTimeSolution solution = new MaxTimeSolution(problem.Size, true);
// select a random start point.
int start = OsmSharp.Math.Random.StaticRandomGenerator.Get().Generate(problem.Size);
// start the first tour.
int placed = 0;
int previous = -1;
// place the first customer.
double weight = 0;
double total_weight = 0;
IRoute route = solution.Add(start);
previous = start;
while (placed < problem.Size)
{
// get the next customer from the tsp solution.
int next = tsp_solution.GetNeigbours(previous)[0];
// get the weight to the current start.
double weight_to_next = problem.WeightMatrix[previous][next];
double weight_to_start = problem.WeightMatrix[next][start];
total_weight = calculator.CalculateOneRouteIncrease(
weight, weight_to_next + weight_to_start);
weight = calculator.CalculateOneRouteIncrease(
weight, weight_to_next);
if (total_weight > problem.Max.Value)
{ // start a new route.
route = solution.Add(next);
weight = 0;
}
else
{ // just insert the next customer.
route.InsertAfter(previous, next);
//route.InsertAfterAndRemove(previous, next, -1);
}
// set the previous.
previous = next;
placed++;
}
if (!solution.IsValid())
{
throw new Exception();
}
StringBuilder builder = new StringBuilder();
builder.Append("[");
total_weight = 0;
for (int idx = 0; idx < solution.Count; idx++)
{
//IRoute route = routes.Route(idx);
route = solution.Route(idx);
weight = calculator.CalculateOneRoute(route);
builder.Append(" ");
builder.Append(weight);
builder.Append(" ");
total_weight = total_weight + weight;
}
builder.Append("]");
builder.Append(total_weight);
builder.Append(": ");
builder.Append(calculator.Calculate(solution));
Console.WriteLine(builder.ToString());
return(solution);
}
/// <summary>
/// Executes a solver procedure.
/// </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);
// keep placing customer until none are left.
List <int> customers = new List <int>(problem.Customers);
while (customers.Count > 0)
{
// select a customer using some heuristic.
int customer_idx = OsmSharp.Math.Random.StaticRandomGenerator.Get().Generate(customers.Count);
int customer = customers[customer_idx];
customers.Remove(customer);
// start a route r.
double current_route_weight = 0;
IRoute current_route = solution.Add(customer);
//Console.WriteLine("Starting new route with {0}", customer);
while (customers.Count > 0)
{
// calculate the best placement.
CheapestInsertionResult result =
CheapestInsertionHelper.CalculateBestPlacement(problem, current_route, customers);
// calculate the new weight.
double potential_weight = calculator.CalculateOneRouteIncrease(current_route_weight, result.Increase);
// cram as many customers into one route as possible.
if (potential_weight < problem.Max.Value)
{
// insert the customer, it is
customers.Remove(result.Customer);
//current_route.InsertAfterAndRemove(result.CustomerBefore, result.Customer, result.CustomerAfter);
current_route.InsertAfter(result.CustomerBefore, result.Customer);
current_route_weight = potential_weight;
//// improve if needed.
////if (improvement_probalitity > OsmSharp.Math.Random.StaticRandomGenerator.Get().Generate(1))
//if (((problem.Size - customers.Count) % _k) == 0)
//{ // an improvement is descided.
// current_route_weight = this.ImproveIntraRoute(problem,
// current_route, current_route_weight);
//}
}
else
{// ok we are done!
//// apply the intra-route heuristics.
//for (int route_idx = 0; route_idx < solution.Count - 1; route_idx++)
//{ // apply the intra-route heurstic between the new and all existing routes.
// this.ImproveInterRoute(problem, solution.Route(route_idx), current_route);
//}
//// apply the inter-route heuristics.
//for (int route_idx = 0; route_idx < solution.Count; route_idx++)
//{ // apply heurstic for each route.
// IRoute route = solution.Route(route_idx);
// this.ImproveIntraRoute(problem, current_route, current_route_weight);
//}
// break the route.
break;
}
}
}
return(solution);
}
/// <summary>
/// Executes a solver procedure.
/// </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);
// keep placing customer until none are left.
List<int> customers = new List<int>(problem.Customers);
while (customers.Count > 0)
{
// select a customer using some heuristic.
int customer_idx = OsmSharp.Tools.Math.Random.StaticRandomGenerator.Get().Generate(customers.Count);
int customer = customers[customer_idx];
customers.Remove(customer);
// start a route r.
double current_route_weight = 0;
IRoute current_route = solution.Add(customer);
//Console.WriteLine("Starting new route with {0}", customer);
while (customers.Count > 0)
{
// calculate the best placement.
CheapestInsertionResult result =
CheapestInsertionHelper.CalculateBestPlacement(problem, current_route, customers);
// calculate the new weight.
double potential_weight = calculator.CalculateOneRouteIncrease(current_route_weight, result.Increase);
// cram as many customers into one route as possible.
if (potential_weight < problem.Max.Value)
{
// insert the customer, it is
customers.Remove(result.Customer);
//current_route.InsertAfterAndRemove(result.CustomerBefore, result.Customer, result.CustomerAfter);
current_route.InsertAfter(result.CustomerBefore, result.Customer);
current_route_weight = potential_weight;
//// improve if needed.
////if (improvement_probalitity > OsmSharp.Tools.Math.Random.StaticRandomGenerator.Get().Generate(1))
//if (((problem.Size - customers.Count) % _k) == 0)
//{ // an improvement is descided.
// current_route_weight = this.ImproveIntraRoute(problem,
// current_route, current_route_weight);
//}
}
else
{// ok we are done!
//// apply the intra-route heuristics.
//for (int route_idx = 0; route_idx < solution.Count - 1; route_idx++)
//{ // apply the intra-route heurstic between the new and all existing routes.
// this.ImproveInterRoute(problem, solution.Route(route_idx), current_route);
//}
//// apply the inter-route heuristics.
//for (int route_idx = 0; route_idx < solution.Count; route_idx++)
//{ // apply heurstic for each route.
// IRoute route = solution.Route(route_idx);
// this.ImproveIntraRoute(problem, current_route, current_route_weight);
//}
// break the route.
break;
}
}
}
return solution;
}
/// <summary>
/// Selects a new seed customer.
/// </summary>
/// <param name="problem"></param>
/// <param name="calculator"></param>
/// <param name="solution"></param>
/// <param name="customers"></param>
/// <returns></returns>
private int SelectSeed(MaxTimeProblem problem, MaxTimeCalculator calculator,
MaxTimeSolution solution, List<int> customers)
{
int selected_customer = -1;
double max_distance = double.MaxValue;
foreach (int customer_to_check in customers)
{
SortedDictionary<double, List<int>> neighbours = new SortedDictionary<double, List<int>>();
for (int idx = 0; idx < customers.Count; idx++)
{
int customer = customers[idx];
if (customer != customer_to_check)
{
double weight = problem.WeightMatrix[customer_to_check][customer] +
problem.WeightMatrix[customer_to_check][customer];
List<int> customers_list = null;
if (!neighbours.TryGetValue(weight, out customers_list))
{
customers_list = new List<int>();
neighbours.Add(weight, customers_list);
}
customers_list.Add(customer);
}
}
double nearest_neighbour_average = 0;
int neighbour_count = 20;
int neighbour_counted = 0;
foreach (KeyValuePair<double, List<int>> pair in neighbours)
{
foreach (int customer in pair.Value)
{
if (neighbour_counted < neighbour_count)
{
neighbour_counted++;
nearest_neighbour_average = nearest_neighbour_average +
pair.Key;
}
else
{
break;
}
}
}
if (max_distance > nearest_neighbour_average)
{
max_distance = nearest_neighbour_average;
selected_customer = customer_to_check;
}
}
return selected_customer;
}
internal override MaxTimeSolution Solve(MaxTimeProblem problem)
{
MaxTimeCalculator calculator = new MaxTimeCalculator(
problem);
// generate a ATSP solution.
IRoute tsp_solution = _tsp_solution;
if (tsp_solution == null)
{
tsp_solution = _tsp_solver.Solve(new TSPProblem(problem));
}
// generate subtours from this solution.
MaxTimeSolution solution = new MaxTimeSolution(problem.Size, true);
// select a random start point.
int start = OsmSharp.Math.Random.StaticRandomGenerator.Get().Generate(problem.Size);
// start the first tour.
int placed = 0;
int previous = -1;
// place the first customer.
double weight = 0;
double total_weight = 0;
IRoute route = solution.Add(start);
previous = start;
while (placed < problem.Size)
{
// get the next customer from the tsp solution.
int next = tsp_solution.GetNeigbours(previous)[0];
// get the weight to the current start.
double weight_to_next = problem.WeightMatrix[previous][next];
double weight_to_start = problem.WeightMatrix[next][start];
total_weight = calculator.CalculateOneRouteIncrease(
weight, weight_to_next + weight_to_start);
weight = calculator.CalculateOneRouteIncrease(
weight, weight_to_next);
if (total_weight > problem.Max.Value)
{ // start a new route.
route = solution.Add(next);
weight = 0;
}
else
{ // just insert the next customer.
route.InsertAfter(previous, next);
//route.InsertAfterAndRemove(previous, next, -1);
}
// set the previous.
previous = next;
placed++;
}
if (!solution.IsValid())
{
throw new Exception();
}
StringBuilder builder = new StringBuilder();
builder.Append("[");
total_weight = 0;
for (int idx = 0; idx < solution.Count; idx++)
{
//IRoute route = routes.Route(idx);
route = solution.Route(idx);
weight = calculator.CalculateOneRoute(route);
builder.Append(" ");
builder.Append(weight);
builder.Append(" ");
total_weight = total_weight + weight;
}
builder.Append("]");
builder.Append(total_weight);
builder.Append(": ");
builder.Append(calculator.Calculate(solution));
OsmSharp.Logging.Log.TraceEvent("TSPPlacementSolver", TraceEventType.Information, builder.ToString());
return solution;
}
/// <summary>
/// Executes a solver procedure.
/// </summary>
/// <param name="problem"></param>
/// <returns></returns>
internal override MaxTimeSolution Solve(MaxTimeProblem problem)
{
MaxTimeCalculator calculator = new MaxTimeCalculator(problem);
// get the seed customers.
ICollection <int> seeds = _seed_selector.SelectSeeds(
problem, _k);
double[] weights = new double[seeds.Count];
// start the seed routes.
List <int> selectable_customers = problem.Customers;
MaxTimeSolution routes = new MaxTimeSolution(
problem.Size, true);
foreach (int seed in seeds)
{
routes.Add(seed);
selectable_customers.Remove(seed);
}
if (!routes.IsValid())
{
throw new Exception();
}
// keep a list of cheapest insertions.
IInsertionCosts costs = new BinaryHeapInsertionCosts();
// keep looping until all customers have been placed.
while (selectable_customers.Count > 0)
{
// try and place into every route.
CheapestInsertionResult best_result = new CheapestInsertionResult();
best_result.Increase = float.MaxValue;
int best_route_idx = -1;
CheapestInsertionResult best_result_above_max = new CheapestInsertionResult();
best_result_above_max.Increase = float.MaxValue;
int best_route_above_max_idx = -1;
for (int route_idx = 0; route_idx < routes.Count; route_idx++)
{
IRoute current_route = routes.Route(route_idx);
// choose the next customer.
CheapestInsertionResult result =
CheapestInsertionHelper.CalculateBestPlacement(problem, current_route, selectable_customers, costs);
if (result.Customer == result.CustomerAfter)
{
throw new Exception();
}
// get the current weight
double weight = weights[route_idx];
if (result.Increase < best_result.Increase)
{
if (weight + result.Increase + calculator.DeliveryTime < problem.Max.Value)
{ // route will still be inside bounds.
best_result = result;
best_route_idx = route_idx;
}
else
{ // route will become above max.
if (result.Increase < best_result_above_max.Increase)
{
best_result_above_max = result;
best_route_above_max_idx = route_idx;
}
}
}
}
// do the placement if a placement is found without max violation.
// else do the placement in the above max route.
CheapestInsertionResult placement_result = new CheapestInsertionResult();
placement_result.Increase = double.MaxValue;
int placement_result_idx = -1;
if (best_route_idx >= 0)
{ // best placement found.
placement_result = best_result;
placement_result_idx = best_route_idx;
}
else
{ // best placement found but only above max.
placement_result = best_result_above_max;
placement_result_idx = best_route_above_max_idx;
}
// do the actual placement.
weights[placement_result_idx] = calculator.CalculateOneRouteIncrease(
weights[placement_result_idx], placement_result.Increase);
selectable_customers.Remove(placement_result.Customer);
//routes.Route(placement_result_idx).InsertAfterAndRemove(
// placement_result.CustomerBefore, placement_result.Customer, placement_result.CustomerAfter);
routes.Route(placement_result_idx).InsertAfter(
placement_result.CustomerBefore, placement_result.Customer);
if (!routes.IsValid())
{
throw new Exception();
}
}
return(routes);
}
/// <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);
}
/// <summary>
/// Selects a new seed customer.
/// </summary>
/// <param name="problem"></param>
/// <param name="calculator"></param>
/// <param name="solution"></param>
/// <param name="customers"></param>
/// <returns></returns>
private int SelectSeed(MaxTimeProblem problem, MaxTimeCalculator calculator,
MaxTimeSolution solution, List<int> customers)
{
// select the customer farthest from the depot.
int selectedCustomer = -1;
double maxDistance = double.MinValue;
foreach (int customerToCheck in customers)
{
double distance = problem.WeightMatrix[0][customerToCheck] +
problem.WeightMatrix[customerToCheck][0];
if (distance > maxDistance)
{
maxDistance = distance;
selectedCustomer = customerToCheck;
}
}
return selectedCustomer;
}
