// two approximation edge selector for minimum spanning tree
void twoApproximation(GraphContainer* container, Leaf** treeRoot) {
// select the relevant nodes to the tree building algorithm
printf("Node selector for 2-approximation.\n");
// reset container internals
resetContainer(container);
// find the minimum spanning tree
printf("Finding the minimum spanning tree.\n");
GraphNode* root = NULL;
minimumSpanningTree(container, &root);
// print the root node pointer
// printf("Root node pointer: %p\n\n", root);
// return a bad root, if the graph root is null
if (root == NULL) {
(*treeRoot) = NULL;
return;
}
// get a leaf and set the root
(*treeRoot) = (Leaf*) malloc(sizeof(Leaf));
(*treeRoot)->root = 1;
(*treeRoot)->data = root->data;
// build the tree
buildTree(root, treeRoot);
}
CGraph CPathFinder::kruskalFindMST() const
{
std::vector<CEdge> edges = getAllEdges();
std::sort(edges.begin(), edges.end());
CDisjointSetUnion disjointSetUnion;
disjointSetUnion.makeFullUnion(points.size());
CGraph minimumSpanningTree(pointsAmount);
for (CEdge currentEdge : edges)
{
if (disjointSetUnion.find(currentEdge.firstVertexIndex) != disjointSetUnion.find(currentEdge.secondVertexIndex))
{
minimumSpanningTree.addEdgeUndirected(currentEdge);
disjointSetUnion.unite(currentEdge.firstVertexIndex, currentEdge.secondVertexIndex);
}
}
return minimumSpanningTree;
}
int main()
{
Set<nodeT *> graph;
Map<nodeT *> graphMap;
InitGraphics();
SetWindowTitle("Pathfinder");
string backgroundFile;
bool timeToQuit = false;
cout << "This masterful piece of work is a graph extravaganza!" << endl;
while (true) {
cout << "Your options are:" << endl;
cout << "(1) Choose a new graph data file" << endl;
cout << "(2) Find shortest path using Dijkstra's algorithm" << endl;
cout << "(3) Compute the minimal spanning tree using Kruskal's algorithm" << endl;
cout << "(4) Determine if the graph has cycles" << endl;
cout << "(5) Quit" << endl;
cout << "Enter choice: ";
int choice = GetInteger();
string datafile;
void UpdateDisplay();
switch (choice) {
case 1:
cout << "Enter the name of the data file: ";
datafile = GetLine();
//datafile = "Small.txt";
//datafile = "USA.txt";
//datafile = "Stanford.txt";
graph.clear();
graphMap.clear();
backgroundFile = ReadGraph(graph, graphMap, datafile);
break;
case 2:
if (backgroundFile == "") {
cout << "No file is specified" << endl;
}
else {
UpdateDisplay();
MovePen(0,0);
DrawNamedPicture(backgroundFile);
DrawNodesAndArcs(graph);
cout << "(2) Finding shortest path using Dijkstra's algorithm" << endl;
HandleShortestPath(graph);
}
break;
case 3:
if (backgroundFile == "") {
cout << "No file is specified" << endl;
}
else {
cout << "(3) Computing the minimal spanning tree using Kruskal's algorithm" << endl;
UpdateDisplay();
MovePen(0,0);
DrawNamedPicture(backgroundFile);
//DrawNodesAndArcs(graph);
minimumSpanningTree(graph, graphMap);
}
break;
case 4:
if (backgroundFile == "") {
cout << "No file is specified" << endl;
}
else {
graphT graph2;
graph2.allNodes = graph;
cout << "(4) Determining if the graph has cycles" << endl;
if (IsCyclicGraph(graph2))
cout << "Yes, it is cyclic" << endl;
else
cout << "No, it is not cyclic" << endl;
}
break;
case 5:
cout << "Thanks for using Pathfinder. Bye!" << endl;
timeToQuit = true;
break;
default:
cout << "Invalid choice" << endl;
break;
}
if (timeToQuit) break;
}
return (0);
}
