//Methods whos primary purpose is to assist other methods
public Edge firstBackTrackEdge(Graph g, List <Edge> path)
{
Edge lastMove = path[path.Count - 1];
path.Remove(lastMove);
g.addBackEdgeSet(lastMove);
g.addBackOtherEdges(lastMove.vertexTwo(), lastMove, coveredVertices(path));
g.addBackVertex(lastMove.vertexTwo());
Edge chosenEdge = selectShortestEdge(g, lastMove.vertexOne());
while (chosenEdge == null)
{
lastMove = path[path.Count - 1];
path.Remove(lastMove);
g.addBackEdgeSet(lastMove);
g.addBackVertex(lastMove.vertexTwo());
chosenEdge = selectShortestEdge(g, lastMove.vertexOne());
g.addBackOtherEdges(lastMove.vertexTwo(), lastMove, coveredVertices(path));
}
return(chosenEdge);
}
public string GeneralAlgorithm(Graph g)
{
DateTime start = DateTime.Now;
Graph gCopy = g.Copy();
bool backTrack = false;
List <Edge> path = new List <Edge>();
Edge startEdge = selectShortestEdge(gCopy, 1);
justRemovedEdge = startEdge;
path.Add(startEdge);
gCopy.removeEdges(gCopy.listEdges(1));
gCopy.removeVertex(justRemovedEdge.vertexOne());
gCopy.removeVertex(justRemovedEdge.vertexTwo());
gCopy.removeEdge(startEdge);
while (gCopy.numberOfVerticesRemaining() > 0)
{
Edge chosenEdge = null;
if (!backTrack)
{
chosenEdge = selectShortestEdge(gCopy, justRemovedEdge.vertexTwo());
}
else
{
chosenEdge = firstBackTrackEdge(gCopy, path);
if (path.Count > 0)
{
justRemovedEdge = path[path.Count - 1];
}
}
if (chosenEdge != null)
{
path.Add(chosenEdge);
gCopy.removeEdges(gCopy.listEdges(justRemovedEdge.vertexTwo()));
gCopy.removeVertex(chosenEdge.vertexOne());
gCopy.removeVertex(chosenEdge.vertexTwo());
gCopy.removeEdge(chosenEdge);
justRemovedEdge = chosenEdge;
backTrack = false;
}
else if (gCopy.numberOfVerticesRemaining() > 0)
{
backTrack = true;
}
}
DateTime stop = DateTime.Now;
TimeSpan timeDiff = (stop - start);
string outputString = String.Format("Time Taken: {0}:{1}:{2}:{3}\n", timeDiff.Days, timeDiff.Hours, timeDiff.Minutes, timeDiff.Seconds) + "Path: " + printEdges(path) + "\nDistance: " + pathDistance(path);
return(outputString);
}
public List <Edge> findRandomHamiltonianPath(Graph g, int startVertex)
{
//Make copy of the copy to pass into another run if the the current run fails
Graph gCopy = g.Copy();
List <Edge> path = new List <Edge>();
Edge startEdge = selectRandomEdge(gCopy, startVertex);
justRemovedEdge = startEdge;
path.Add(startEdge);
while (gCopy.numberOfVerticesRemaining() > 0)
{
Edge chosenEdge = selectRandomEdge(gCopy, justRemovedEdge.vertexTwo());
if (chosenEdge != null)
{
path.Add(chosenEdge);
justRemovedEdge = chosenEdge;
}
else
{
//Redo if vertices remain untouched
return(findRandomHamiltonianPath(g, startVertex));
}
}
return(path);
}
public string Greedy(Graph g)
{
DateTime start = DateTime.Now;
List <Edge> eulerCircuit = new List <Edge>();
List <Edge> finalEulerCircuit = new List <Edge>();
List <List <Edge> > iterations = new List <List <Edge> >();
bool firstVertexEntered = false;
//Gets the first vertex of circuit as vertexOne. The rest should all be vertexTwo.
while (g.numberofEdgesRemaining() > 0)
{
if (!firstVertexEntered)
{
//Finds first edge available from the vertices in the current eu
appendEulerCircuit(g, eulerCircuit, g.findFirstRemainingVertex(finalEulerCircuit));
finalEulerCircuit.Clear();
firstVertexEntered = true;
}
else if (g.listEdges(justRemovedEdge.vertexTwo()).Count > 0)
{
appendEulerCircuit(g, eulerCircuit, justRemovedEdge.vertexTwo());
}
else
{
appendEulerCircuit(g, eulerCircuit, justRemovedEdge.vertexTwo());
iterations.Add(new List <Edge>(eulerCircuit));
finalEulerCircuit = insertIterations(iterations);
eulerCircuit.Clear();
firstVertexEntered = false;
}
}
iterations.Add(new List <Edge>(eulerCircuit));
//eulerCircuit.Clear();
//eulerCircuit = insertIterations(iterations);
finalEulerCircuit.Clear();
finalEulerCircuit = insertIterations(iterations);
DateTime stop = DateTime.Now;
TimeSpan timeDiff = (stop - start);
string outputString = String.Format("Time Taken: {0}:{1}:{2}:{3}\n", timeDiff.Days, timeDiff.Hours, timeDiff.Minutes, timeDiff.Seconds) + "Euler Circuit: " + printEdges(finalEulerCircuit) + "\nDistance: " + pathDistance(finalEulerCircuit);
return(outputString);
}
public Edge selectEdge(List <Edge> edgeList, int index)
{
Edge e = edgeList[index];
removeEdges(edgeList);
removeVertex(e.vertexOne());
removeVertex(e.vertexTwo());
return(e);
}
