stackP sp_Duplicate(stackP theStack)
{
stackP newStack = sp_New(theStack->capacity);
if (newStack == NULL)
return NULL;
if (theStack->size > 0)
memcpy(newStack->S, theStack->S, theStack->size*sizeof(int));
return newStack;
}
int gp_ColorVertices(graphP theGraph)
{
ColorVerticesContext *context = NULL;
int v, deg;
int u=0, w=0, contractible;
// Attach the algorithm if it is not already attached
if (gp_AttachColorVertices(theGraph) != OK)
return NOTOK;
// Ensure there is enough stack to perform this operation.
// At a maximum, the graph reduction will push 7N+M integers.
// One integer is pushed per edge that is hidden. Plus, whether
// a vertex is hidden or identified with another vertex, 7 integers
// are used to store enough information to restore it.
if (sp_NonEmpty(theGraph->theStack))
return NOTOK;
if (sp_GetCapacity(theGraph->theStack) < 7*theGraph->N + theGraph->M)
{
stackP newStack = sp_New(7*theGraph->N + theGraph->M);
if (newStack == NULL)
return NOTOK;
sp_Free(&theGraph->theStack);
theGraph->theStack = newStack;
}
// Get the extension context and reinitialize it if necessary
gp_FindExtension(theGraph, COLORVERTICES_ID, (void *)&context);
if (context->color[0] > -1)
_ColorVertices_Reinitialize(context);
// Initialize the degree lists, and provide a color for any trivial vertices
for (v = 0; v < theGraph->N; v++)
{
deg = gp_GetVertexDegree(theGraph, v);
_AddVertexToDegList(context, theGraph, v, deg);
if (deg == 0)
context->color[v] = 0;
}
// Initialize the visited flags so they can be used during reductions
_FillVisitedFlags(theGraph, 0);
// Reduce the graph using minimum degree selection
while (context->numVerticesToReduce > 0)
{
v = _GetVertexToReduce(context, theGraph);
// Find out if v is contractible and the neighbors to contract
contractible = _GetContractibleNeighbors(context, v, &u, &w);
// Remove the vertex from the graph. This calls the fpHideEdge
// overload, which performs the correct _RemoveVertexFromDegList()
// and _AddVertexToDegList() operations on v and its neighbors.
if (gp_HideVertex(theGraph, v) != OK)
return NOTOK;
// If v was contractibile, then identify u and w
if (contractible)
{
if (gp_IdentifyVertices(theGraph, u, w, NIL) != OK)
return NOTOK;
}
}
// Restore the graph one vertex at a time, coloring each vertex distinctly
// from its neighbors as it is restored.
context->colorDetector = (int *) calloc(theGraph->N, sizeof(int));
if (context->colorDetector == NULL)
return NOTOK;
if (gp_RestoreVertices(theGraph) != OK)
return NOTOK;
free(context->colorDetector);
context->colorDetector = NULL;
return OK;
}
