//add links to the components connecting it with the initVertex
void AddComponent(int compID, SingleSourceShortestPaths shortestPaths)
{
this.joinedComps[compID] = true;
//take a node clsosest to the initVertex
int node = -1;
int dist = Int32.MaxValue;
foreach (Edge l in this.comps[compID])
{
if (shortestPaths.GetDistTo(l.source) < dist)
{
dist = shortestPaths.GetDistTo(l.source);
node = l.source;
}
if (shortestPaths.GetDistTo(l.target) < dist)
{
dist = shortestPaths.GetDistTo(l.target);
node = l.target;
}
}
//find a link entering the component from the outside
Edge link = null;
while (this.nodesToCompIds[node] == compID)
{
if (node == this.initVertex) //this component is already connected to the initVertex
{
return;
}
link = shortestPaths.Pred[node];
node = link.source;
}
while (true)
{
this.linksToCompIDs[link] = this.closureID;
int sourceCompID = nodesToCompIds[link.source];
if (sourceCompID == -1)
{
link = shortestPaths.Pred[link.source];
nodesToCompIds[link.target] = closureID;
}
else if (sourceCompID == closureID)
{
break;
}
else //we hit a component from comps
{
this.joinedComps[sourceCompID] = true;
break;
}
}
}
void Process()
{
if (this.numberOfVertices == 0)
{
return;
}
if (this.mustEdges == null || this.mustEdges.Length == 0)
{
newML = new Edge[0];
newOL = this.optionalEdges;
return;
}
//first check with the hope that we are fine
//that means that we have only one weakly
//connected component containing the initVertex
if (comps.Length == 1)
{
foreach (Edge link in comps[0])
{
if (this.initVertex == link.target || this.initVertex == link.source)
{
newML = this.mustEdges;
newOL = this.optionalEdges;
return;
}
}
}
//connect each component with the initial vertex
//nothing is joined at the beginning
joinedComps = new bool[comps.Length];
#region organizing the node to component id map
this.nodesToCompIds = new int[this.numberOfVertices];
for (int i = 0; i < nodesToCompIds.Length; i++)
{
nodesToCompIds[i] = -1; //does not belong to any component
}
for (int compID = 0; compID < comps.Length; compID++)
{
foreach (Edge link in comps[compID])
{
nodesToCompIds[link.source] = nodesToCompIds[link.target] = compID;
}
}
//if initVertex does not belong to any components mark it as belonging to the
//bigger component
if (this.nodesToCompIds[this.initVertex] == -1)
{
this.nodesToCompIds[this.initVertex] = this.closureID;
}
else
{
this.joinedComps[this.nodesToCompIds[this.initVertex]] = true;
}
#endregion
SingleSourceShortestPaths shortestPaths =
new SingleSourceShortestPaths(
new BasicGraph(this.initVertex, this.mustEdges, this.optionalEdges),
this.initVertex);
shortestPaths.Calculate();
//use the spanning tree of the SingleSourceShortestPaths
//to connect the components with initVertex
if (this.nodesToCompIds[this.initVertex] == -1)
{
this.nodesToCompIds[this.initVertex] = this.closureID;
}
bool done = false;
//add the first component - may be is the only one
AddComponent(0, shortestPaths);
while (!done)
{
done = true;
//find non-joined component
for (int compID = 0; compID < comps.Length; compID++)
{
if (joinedComps[compID] == false)
{
done = false;
AddComponent(compID, shortestPaths);
continue;
}
}
}
this.newML = new Edge[linksToCompIDs.Count];
this.linksToCompIDs.Keys.CopyTo(this.newML, 0);
this.newOL = new Edge[this.optionalEdges.Length - newML.Length + mustEdges.Length];
int j = 0;
foreach (Edge l in optionalEdges)
{
if (linksToCompIDs.Contains(l) == false)
{
this.newOL[j++] = l;
}
}
}