public void solveProblemGreedy()
{
//initialize BSSF with a greedy algorithm
Stopwatch stopwatch = new Stopwatch();
stopwatch.Start();
Algorithms algorithms = new Algorithms();
bssf = new TSPSolution(algorithms.greedy(Cities));
stopwatch.Stop();
Program.MainForm.tbCostOfTour.Text = " " + bssf.costOfRoute();
Program.MainForm.tbElapsedTime.Text = " " + stopwatch.Elapsed.TotalSeconds;
// do a refresh.
Program.MainForm.Invalidate();
}
//Our TSP
internal void solveProblemTabu()
{
int bssfUpdates = 0;
Algorithms algorithms = new Algorithms();
bssf = new TSPSolution(algorithms.greedy(Cities));
TSPSolution currentSolution = new TSPSolution(bssf.Route);
int size = Convert.ToInt32(Program.MainForm.textBoxTabuSize.Text);
TabuList tabuList = new TabuList(size);//set capacity of tabuList
int timeSeconds = Convert.ToInt32(Program.MainForm.textBoxTime.Text);
double totalTime = 0;
Stopwatch stopwatch = new Stopwatch();
stopwatch.Start();
while(stopwatch.Elapsed.TotalSeconds < timeSeconds)//run for 600 seconds, 10 minutes
{
currentSolution = findBestCandidate(currentSolution, tabuList);
if(currentSolution.cost < bssf.cost)
{
bssf = new TSPSolution(currentSolution.Route);
totalTime = stopwatch.Elapsed.TotalSeconds;
bssfUpdates++;
}
tabuList.addSolution(currentSolution);
}
stopwatch.Stop();
Program.MainForm.tbCostOfTour.Text = " " + bssf.cost;
Program.MainForm.tbElapsedTime.Text = " " + totalTime;
//Program.MainForm.tbElapsedTime.Text = " " + stopwatch.Elapsed.TotalSeconds;
Program.MainForm.toolStripTextBox1.Text = " " + bssfUpdates;
//print bssf update number
// do a refresh.
Program.MainForm.Invalidate();
}
/// <summary>
/// solve the problem. This is the entry point for the solver when the run button is clicked
/// right now it just picks a simple solution.
/// </summary>
public void solveProblemBandB()
{
//initialize BSSF with a greedy algorithm
Algorithms algorithms = new Algorithms();
bssf = new TSPSolution(algorithms.greedy(Cities));
Node.bssf = bssf.costOfRoute();
int maxQsize = 0;
int totalStates = 0;
int timeSeconds = Convert.ToInt32(Program.MainForm.textBoxTime.Text);
//set up priority queue and stopwatch
PriorityQueue PQ = new PriorityQueue();
PQ.insert(new Node(Cities));
Stopwatch stopwatch = new Stopwatch();
stopwatch.Start();
while(PQ.getSize() > 0 && stopwatch.Elapsed.TotalSeconds < timeSeconds)
{
//pop node off of queue and check lower bound against bssf
Node node = PQ.deleteMin();
if(node.lowerBound > Node.bssf)
{
Node.prunes++;
break;
}
Node include = null;
Node exclude = null;
double maxDif = Double.NegativeInfinity;
//search for include/exclude edge that gives max difference in lower bound
double[,] matrix = node.rCmatrix;
for (int i = 0; i < node.matrixLength; i++)
{
if (node.exited[i] == -1)
{
for (int j = 0; j < node.matrixLength; j++)
{
if (matrix[i, j] == 0)
{
Node tempInclude = new Node(node, true, i, j);
Node tempExclude = new Node(node, false, i, j);
double potentialMaxDif = tempExclude.lowerBound - tempInclude.lowerBound;
if (potentialMaxDif > maxDif)
{
maxDif = potentialMaxDif;
include = tempInclude;
exclude = tempExclude;
}
}
}
}
}
//check if found a bssf
if(include.totalEdges == include.matrixLength && include.lowerBound < Node.bssf)
{
Node.bssfUpdates++;
Node.bssf = include.lowerBound;
Node.bssfNode = include;
}
else if(include.lowerBound < Node.bssf)//add include node to queue
{
PQ.insert(include);
int currentQSize = PQ.getSize();
if(currentQSize > maxQsize)
{
maxQsize = currentQSize;
}
}
else//prune include node
{
Node.prunes++;
}
if(exclude.lowerBound < Node.bssf)//add exclude node to queue
{
PQ.insert(exclude);
int currentQSize = PQ.getSize();
if (currentQSize > maxQsize)
{
maxQsize = currentQSize;
}
}
else//prune exclude node
{
Node.prunes++;
}
totalStates += 2;//2 states are created per while-loop iteration
}
stopwatch.Stop();
//if stopwatch is < 30, then we have found an optimal solution
bool isOptimal = false;
if(stopwatch.Elapsed.TotalSeconds < timeSeconds)
{
isOptimal = true;
}
//prune number of items left in the queue
Node.prunes += PQ.getSize();
//if a bssf has been found better than the greedy solution
if(Node.bssfNode != null)
{
Node solution = Node.bssfNode;
ArrayList route = solution.getRoute(Cities);
// call this the best solution so far. bssf is the route that will be drawn by the Draw method.
bssf = new TSPSolution(route);
}
//display stats
if (isOptimal)
{
Program.MainForm.tbCostOfTour.Text = " " + bssf.costOfRoute() + "*";
}
else
{
Program.MainForm.tbCostOfTour.Text = " " + bssf.costOfRoute();
}
Program.MainForm.tbElapsedTime.Text = " " + stopwatch.Elapsed.TotalSeconds;
// do a refresh.
Program.MainForm.Invalidate();
//print more stats
Console.WriteLine();
Console.WriteLine("Max # of stored states: " + maxQsize);
Console.WriteLine("# of BSSF updates: " + Node.bssfUpdates);
Console.WriteLine("Total # of states created: " + totalStates);
Console.WriteLine("Total # of states pruned: " + Node.prunes);
Node.resetStaticVariables();
}