public TSPath(TSPath parent, int destination)
{
isFinished = false;
this.destination = destination;
this.parent = parent;
int sourceCity = parent.destination;
minDistance = parent.minDistance + parent.distances[sourceCity, this.destination];
level = parent.level + 1;
cityPathOrder = (int[])parent.cityPathOrder.Clone();
cityPathOrder[destination] = level;
if (parent.cityPathOrder[destination] > 0)
{
if (level == numCities + 1 && destination == 0)
{
cityPathOrder[0] = 1;//this is to reset the first city to being first not last
//minDistance += parent.distances[sourceCity, destination];
score = 0;
isFinished = true;
return;
}
minDistance = double.PositiveInfinity;
score = double.PositiveInfinity;
return;
}
if (double.IsPositiveInfinity(parent.distances[sourceCity, destination]))
{
minDistance = double.PositiveInfinity;
score = double.PositiveInfinity;
return;
}
distances = (double[, ])parent.distances.Clone();
commonInitialization();
}
public int CompareTo(Object obj)
{
if (obj == null)
{
return(1);
}
TSPath otherTemperature = obj as TSPath;
if (otherTemperature != null)
{
return(this.score.CompareTo(otherTemperature.score));
}
else
{
throw new ArgumentException("Object is not a TSPath");
}
}
// used to initialize each city
public TSPath(City[] cities)
{
isFinished = false;
parent = null;
minDistance = 0;
level = 1;
numCities = cities.Length;
distances = new double[numCities, numCities];
cityPathOrder = new int[numCities];
for (int i = 0; i < numCities; i++)
{
City refCity = cities[i];
for (int j = 0; j < numCities; j++)
{
double distance = refCity.costToGetTo(cities[j]);
distances[i, j] = distance;
}
distances[i, i] = double.PositiveInfinity;
cityPathOrder[i] = 0;
}
cityPathOrder[0] = 1;
commonInitialization();
}
public TSDistance(TSPath path)
{
this.path = path.cityPathOrder;
minDistance = path.getDistance();
}
/// <summary>
/// performs a Branch and Bound search of the state space of partial tours
/// stops when time limit expires and uses BSSF as solution
/// </summary>
/// <returns>results array for GUI that contains three ints: cost of solution, time spent to find solution, number of solutions found during search (not counting initial BSSF estimate)</returns>
public string[] bBSolveProblem()
{
//make first TSPath and add it to the binary heap
MinHeap <TSPath> heap = new MinHeap <TSPath>();
int timeout = TIME_LIMIT * 1000;
Stopwatch stopWatch = new Stopwatch();
stopWatch.Start();
heap.Insert(new TSPath(GetCities()));
MinHeap <TSDistance> minDistances = new MinHeap <TSDistance>();
minDistances.Insert(new TSDistance(heap.Peek()));
double bestPossibleSolution = heap.Peek().getDistance();
int numSolutions = 0;
defaultSolveProblem();
double bestSolutionDistance = costOfBssf();
int[] bssfArray = new int[0];
numStatesCreated = 1;
numStatesPruned = 1;
maxStatesStored = 1;
//repeat following until timeout or best solution found
while (heap.Count != 0 && stopWatch.ElapsedMilliseconds < timeout)
{
maxStatesStored = (maxStatesStored > heap.Count ? maxStatesStored : heap.Count);
TSPath min = heap.ExtractMin();
if (min.isFinished)
{
numSolutions++;
ArrayList Route = new ArrayList();
City[] cities = GetCities();
int[] minArray = min.getPath();
for (int i = 0; i < minArray.Length; i++)
{
Route.Add(cities[minArray[i]]);
}
double minLength = min.getDistance();
TSPSolution solution = new TSPSolution(Route);
if (solution.costOfRoute() < bestSolutionDistance)
{
bssfArray = min.getPath();
bestSolutionDistance = solution.costOfRoute();
bssf = solution;
}
}
else
{
if (min.getDistance() > bestSolutionDistance)
{
numStatesPruned++;
}
else
{
foreach (TSPath child in min.getAllChildren())
{
numStatesCreated++;
if (child.getDistance() < bestSolutionDistance)
{
//minDistances.Insert(new TSDistance(child));
heap.Insert(child);
}
else
{
numStatesPruned++;
}
}
}
}
}
string[] results = new string[3];
/*if(numSolutions > 0)
* {
* ArrayList Route = new ArrayList();
* City[] cities = GetCities();
* for(int i = 0; i < bssfArray.Length; i++)
* {
* Route.Add(cities[bssfArray[i]]);
* }
* bssf = new TSPSolution(Route);
* }*/
results[COST] = costOfBssf().ToString(); // load results into array here, replacing these dummy values
results[TIME] = (((double)stopWatch.ElapsedMilliseconds) / 1000).ToString();
results[COUNT] = numSolutions.ToString();
return(results);
}
