private RouteFound AfterSelectt5(IProblem problem, RouteFound route, EdgeSet X, EdgeSet Y, EdgeList x, EdgeList y)
{
if (x.Count != y.Count)
{
OsmSharp.Tools.Output.OutputStreamHost.Write(string.Empty);
}
int t_1 = x[0].From;
int t_2i_min_1 = y[y.Count - 1].To;
// try and find a better route with t_1.
RouteFound new_route = new RouteFound()
{
RouteWeight = float.MaxValue,
Route = null
};
HashSet<int> exceptions = new HashSet<int>();
int? result = this.SelectX(problem, route.Route, X, Y, x, t_2i_min_1, exceptions);
while (result != null) // do backtacking over x: TODO: improve this and immidiately find the correct tour.
{
int t_2i = result.Value;
exceptions.Add(t_2i);
// step 6.
t_2i = result.Value;
Edge x_edge = new Edge()
{
From = t_2i_min_1,
To = t_2i,
Weight = problem.Weight(t_2i_min_1, t_2i)
};
x.Add(x_edge);
X.Add(x_edge);
// Test the route T' for feasability and weight.
y.Add(new Edge()
{
From = t_2i,
To = t_1,
Weight = problem.Weight(t_2i, t_2i)
});
new_route.Route = this.Replace(route.Route, x, y);
y.RemoveLast(); // remove the perliminary y.
if (x.Count != y.Count + 1)
{
OsmSharp.Tools.Output.OutputStreamHost.Write(string.Empty);
}
if (new_route.Route.IsValid())
{
// stop the search for now if the route is already better.
new_route.RouteWeight = LinKernighanSolver.Weight(problem, new_route.Route);
if (new_route.RouteWeight < route.RouteWeight)
{ // break.
Console.WriteLine("Route {0}:{1}",
new_route.Route.ToString(),
new_route.RouteWeight);
return new_route;
}
// choose next y.
result = this.SelectY(problem, route.Route, X, Y, x, y, null);
if (result != null)
{
int t_2_plus_1 = result.Value;
Edge y_edge = new Edge()
{
From = t_2i,
To = t_2_plus_1,
Weight = problem.Weight(t_2i, t_2_plus_1)
};
y.Add(y_edge);
Y.Add(y_edge);
// choose next.
new_route = this.AfterSelectt5(problem, route, X, Y, x, y);
if (new_route.RouteWeight < route.RouteWeight)
{ // break.
Console.WriteLine("Route {0}:{1}",
new_route.Route.ToString(),
new_route.RouteWeight);
return new_route;
}
// remove y again.
y.RemoveLast();
}
x.RemoveLast();
break; // the other x cannot be valid!
}
// backtrack over x.
x.RemoveLast();
result = this.SelectX(problem, route.Route, X, Y, x, t_2i_min_1, exceptions);
}
if (x.Count != y.Count)
{
OsmSharp.Tools.Output.OutputStreamHost.Write(string.Empty);
}
return new_route;
}
private RouteFound AfterSelectt4(IProblem problem, RouteFound route, EdgeSet X, EdgeSet Y, EdgeList x, EdgeList y)
{
int t_1 = x[0].From;
int t_3 = y[0].To;
int t_4 = x[1].To;
// try and find a better route with t_1.
RouteFound new_route = new RouteFound()
{
RouteWeight = float.MaxValue,
Route = null
};
// choose t_5 for backtracking later.
HashSet<int> t_5_exceptions = new HashSet<int>();
int? result = this.SelectY(problem, route.Route, X, Y, x, y, t_5_exceptions);
while (result != null)
{
// choose t_5.
int t_5 = result.Value;
t_5_exceptions.Add(t_5);
Edge y_2 = new Edge()
{
From = t_4,
To = t_5,
Weight = problem.Weight(t_4, t_5)
};
y.Add(y_2);
Y.Add(y_2);
if (x.Count != y.Count)
{
OsmSharp.Tools.Output.OutputStreamHost.Write(string.Empty);
}
// try and find a better route by selecting more customer.
new_route = this.AfterSelectt5(problem, route, X, Y, x, y);
if (new_route.Route != null &&
new_route.RouteWeight < route.RouteWeight)
{ // trackback to t_1 if a better route is found.
break;
}
// remove and backtrack y_2.
y.RemoveLast();
if (x.Count != y.Count + 1)
{
OsmSharp.Tools.Output.OutputStreamHost.Write(string.Empty);
}
result = this.SelectY(problem, route.Route, X, Y, x, y, t_5_exceptions);
} // choose t_5
return new_route;
}
private RouteFound AfterSelectt2(IProblem problem, RouteFound route, EdgeSet X, EdgeSet Y, EdgeList x)
{
int t_2 = x[0].To;
// try and find a better route with t_1.
RouteFound new_route = new RouteFound()
{
RouteWeight = float.MaxValue,
Route = null
};
// step 4 and step 10.
HashSet<int> t_3_exceptions = new HashSet<int>();
EdgeList y = new EdgeList();
int? result = this.SelectY(problem, route.Route, X, Y, x, y, t_3_exceptions);
while (result != null)
{
// select t_3.
int t_3 = result.Value;
t_3_exceptions.Add(t_3);
// add y_1 to the edge list.
Edge y_edge = new Edge()
{
From = t_2,
To = t_3,
Weight = problem.Weight(t_2, t_3)
};
y.Add(y_edge);
Y.Add(y_edge);
// search route with t_3.
new_route = this.AfterSelectt3(problem, route, X, Y, x, y);
if (new_route.Route != null &&
new_route.RouteWeight < route.RouteWeight)
{ // trackback to t_1 if a better route is found.
break;
}
// remove y_1 again and backtrack.
y.RemoveLast();
if (x.Count != y.Count + 1)
{
OsmSharp.Tools.Output.OutputStreamHost.Write(string.Empty);
}
result = this.SelectY(problem, route.Route, X, Y, x, y, t_3_exceptions);
}
return new_route;
}
private RouteFound AfterSelectt3(IProblem problem, RouteFound route, EdgeSet X, EdgeSet Y, EdgeList x, EdgeList y)
{
int t_1 = x[0].From;
int t_3 = y[0].To;
// try and find a better route with t_1.
RouteFound new_route = new RouteFound()
{
RouteWeight = float.MaxValue,
Route = null
};
// choose t_4 for backtracking later.
HashSet<int> t_4_exceptions = new HashSet<int>();
int? result = this.SelectX(problem, route.Route, X, Y, x, t_3, t_4_exceptions);
while (result != null)
{
// select t_4.
int t_4 = result.Value;
t_4_exceptions.Add(t_4);
// add to x and test with perliminary y.
Edge x_edge = new Edge()
{
From = t_3,
To = t_4,
Weight = problem.Weight(t_3, t_4)
};
x.Add(x_edge);
X.Add(x_edge);
// Test the route T' for feasability and weight.
y.Add(new Edge()
{
From = t_4,
To = t_1,
Weight = problem.Weight(t_4, t_1)
});
new_route.Route = this.Replace(route.Route, x, y);
y.RemoveLast(); // remove the perliminary y.
if (new_route.Route.IsValid())
{
// stop the search for now if the route is already better.
new_route.RouteWeight = LinKernighanSolver.Weight(problem, new_route.Route);
if (new_route.RouteWeight < route.RouteWeight)
{ // break.
Console.WriteLine("Route {0}:{1}",
new_route.Route.ToString(),
new_route.RouteWeight);
x.RemoveLast(); // remove the latest x here!
break;
}
}
// choose t_5 here.
new_route = this.AfterSelectt4(problem, route, X, Y, x, y);
if (new_route.Route != null &&
new_route.RouteWeight < route.RouteWeight)
{ // trackback to t_1 if a better route is found.
break;
}
// reset the new route.
new_route.Route = null;
new_route.RouteWeight = float.MaxValue;
// remove and backtrack x_2.
x.RemoveLast();
if (x.Count != y.Count)
{
OsmSharp.Tools.Output.OutputStreamHost.Write(string.Empty);
}
result = this.SelectX(problem, route.Route, X, Y, x, t_3, t_4_exceptions);
} // choose t_4
return new_route;
}
private RouteFound AfterSelectt1(IProblem problem, RouteFound route, EdgeSet X, EdgeSet Y, int t_1)
{
// try and find a better route with t_1.
RouteFound new_route = new RouteFound()
{
RouteWeight = float.MaxValue,
Route = null
};
// step 3 and step 11.
HashSet<int> t_2_exceptions = new HashSet<int>();
EdgeList x = new EdgeList();
int? result = this.SelectX(problem, route.Route, X, Y, x, t_1, t_2_exceptions);
while (result != null)
{
// select t_2.
int t_2 = result.Value;
t_2_exceptions.Add(t_2);
// add x_1 to the edge list.
Edge x_edge = new Edge()
{
From = t_1,
To = t_2,
Weight = problem.Weight(t_1, t_2)
};
x.Add(x_edge);
X.Add(x_edge);
// search route with t_2.
new_route = this.AfterSelectt2(problem, route, X, Y, x);
if (new_route.Route != null &&
new_route.RouteWeight < route.RouteWeight)
{ // trackback to t_1 if a better route is found.
break;
}
// remove x_1 again and backtrack.
x.RemoveLast();
result = this.SelectX(problem, route.Route, X, Y, x, t_1, t_2_exceptions);
} // step 3 and step 11.
return new_route;
}