graphP MakeGraph(int Size, char command)
{
graphP theGraph;
if ((theGraph = gp_New()) == NULL || gp_InitGraph(theGraph, Size) != OK)
{
ErrorMessage("Error creating space for a graph of the given size.\n");
gp_Free(&theGraph);
return NULL;
}
// Enable the appropriate feature. Although the same code appears in SpecificGraph,
// it is deliberately not separated to a common utility because SpecificGraph is
// used as a self-contained tutorial. It is not that hard to update both locations
// when new algorithms are added.
switch (command)
{
case 'd' : gp_AttachDrawPlanar(theGraph); break;
case '2' : gp_AttachK23Search(theGraph); break;
case '3' : gp_AttachK33Search(theGraph); break;
case '4' : gp_AttachK4Search(theGraph); break;
case 'c' : gp_AttachColorVertices(theGraph); break;
}
return theGraph;
}
void AttachAlgorithm(graphP theGraph, char command)
{
switch (command)
{
case 'd' : gp_AttachDrawPlanar(theGraph); break;
case '2' : gp_AttachK23Search(theGraph); break;
case '3' : gp_AttachK33Search(theGraph); break;
case '4' : gp_AttachK4Search(theGraph); break;
case 'c' : gp_AttachColorVertices(theGraph); break;
}
}
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;
}
int SpecificGraph(char command, char *infileName, char *outfileName, char *outfile2Name)
{
graphP theGraph, origGraph;
platform_time start, end;
int Result;
// Get the filename of the graph to test
if ((infileName = ConstructInputFilename(infileName)) == NULL)
return NOTOK;
// Create the graph and, if needed, attach the correct algorithm to it
theGraph = gp_New();
switch (command)
{
case 'd' : gp_AttachDrawPlanar(theGraph); break;
case '2' : gp_AttachK23Search(theGraph); break;
case '3' : gp_AttachK33Search(theGraph); break;
case '4' : gp_AttachK4Search(theGraph); break;
case 'c' : gp_AttachColorVertices(theGraph); break;
}
// Read the graph into memory
Result = gp_Read(theGraph, infileName);
if (Result == NONEMBEDDABLE)
{
Message("The graph contains too many edges.\n");
// Some of the algorithms will still run correctly with some edges removed.
if (strchr("pdo234", command))
{
Message("Some edges were removed, but the algorithm will still run correctly.\n");
Result = OK;
}
}
// If there was an unrecoverable error, report it
if (Result != OK)
ErrorMessage("Failed to read graph\n");
// Otherwise, call the correct algorithm on it
else
{
// Copy the graph for integrity checking
origGraph = gp_DupGraph(theGraph);
// Run the algorithm
if (strchr("pdo234", command))
{
int embedFlags = GetEmbedFlags(command);
platform_GetTime(start);
// gp_CreateDFSTree(theGraph);
// gp_SortVertices(theGraph);
// gp_Write(theGraph, "debug.before.txt", WRITE_DEBUGINFO);
// gp_SortVertices(theGraph);
Result = gp_Embed(theGraph, embedFlags);
platform_GetTime(end);
Result = gp_TestEmbedResultIntegrity(theGraph, origGraph, Result);
}
else
{
platform_GetTime(start);
if (command == 'c')
{
if ((Result = gp_ColorVertices(theGraph)) == OK)
Result = gp_ColorVerticesIntegrityCheck(theGraph, origGraph);
}
else
Result = NOTOK;
platform_GetTime(end);
}
// Write what the algorithm determined and how long it took
WriteAlgorithmResults(theGraph, Result, command, start, end, infileName);
// Free the graph obtained for integrity checking.
gp_Free(&origGraph);
}
// Report an error, if there was one, free the graph, and return
if (Result != OK && Result != NONEMBEDDABLE)
{
ErrorMessage("AN ERROR HAS BEEN DETECTED\n");
Result = NOTOK;
// gp_Write(theGraph, "debug.after.txt", WRITE_DEBUGINFO);
}
// Provide the output file(s)
else
{
// Restore the vertex ordering of the original graph (undo DFS numbering)
if (strchr("pdo234", command))
gp_SortVertices(theGraph);
// Determine the name of the primary output file
outfileName = ConstructPrimaryOutputFilename(infileName, outfileName, command);
// For some algorithms, the primary output file is not always written
if ((strchr("pdo", command) && Result == NONEMBEDDABLE) ||
(strchr("234", command) && Result == OK))
{
// Do not write the file
}
// Write the primary output file, if appropriate to do so
else
{
gp_Write(theGraph, outfileName, WRITE_ADJLIST);
}
// NOW WE WANT TO WRITE THE SECONDARY OUTPUT FILE
// When called from the menu system, we want to write the planar or outerplanar
// obstruction, if one exists. For planar graph drawing, we want the character
// art rendition. An empty but non-NULL string is passed to indicate the necessity
// of selecting a default name for the second output file.
if (outfile2Name != NULL)
{
if ((command == 'p' || command == 'o') && Result == NONEMBEDDABLE)
{
// By default, use the same name as the primary output filename
if (strlen(outfile2Name) == 0)
outfile2Name = outfileName;
gp_Write(theGraph, outfile2Name, WRITE_ADJLIST);
}
else if (command == 'd' && Result == OK)
{
// By default, add ".render.txt" to the primary output filename
if (strlen(outfile2Name) == 0)
strcat((outfile2Name = outfileName), ".render.txt");
gp_DrawPlanar_RenderToFile(theGraph, outfile2Name);
}
}
}
// Free the graph
gp_Free(&theGraph);
// Flush any remaining message content to the user, and return the result
FlushConsole(stdout);
return Result;
}
