//method finds coloring of graph to minimize conflicts
//returns number of conflicts
int exhaustiveColoring(graph &g, int numColors, int t) {
//vector to hold answer with least conflicts seen so far
//initially ever node is color 1
vector<int> bestAnswer(g.numNodes(), 1);
//vector to hold answer currently being tested
//also set to all color 1
vector<int> currentAnswer = bestAnswer;
//int to hold number of conflicts in bestAnswer
//initialized to max number of cnflicts for given graph
int conflicts = g.numEdges();
//initilize starting time
double startTime = (double) (clock() / CLOCKS_PER_SEC);
//while time elapsed is within given time
while ( (double)(clock() / CLOCKS_PER_SEC) - startTime < t) {
//change graph to have coloration of currentAnswer
for (int i = 0; i < currentAnswer.size(); i++) {
g.setColor(i, currentAnswer[i]);
}
//if current graph is asgood as or better than best graph
//set best graph to current graph
if (g.numConflicts() <= conflicts) {
conflicts = g.numConflicts();
bestAnswer = currentAnswer;
}
//break if all permutations of colors have been tested
//algorithm is done
if (!increment(currentAnswer, numColors)) {
break;
}
}
//set coloration of graph to best rsult
for (int i = 0; i < bestAnswer.size(); i++) {
g.setColor(i, bestAnswer[i]);
}
return conflicts;
}
void prim(graph &g, graph &sf)
// Given a weighted graph g, sets sf equal to a minimum spanning
// forest on g. Uses Prim's algorithm.
{
NodeWeight minWeight = 0;
NodeWeight minR, minP;
bool edgeFound;
g.clearMark();
for(int i=0; i<g.numNodes(); i++)
{
if(!g.isMarked(i))
{
g.mark(i);
for(int j=0; j<g.numNodes()-1; j++)
//start at i and grow a spanning tree untill no more can be added
{
edgeFound = false;
minWeight = MaxEdgeWeight;
for(int r=0; r<g.numNodes(); r++)
{
for(int p=0; p<g.numNodes(); p++)
{
if(g.isEdge(r,p) && g.isMarked(r) && !g.isMarked(p))
{
if(g.getEdgeWeight(r,p) < minWeight)
{
minWeight = g.getEdgeWeight(r,p);
minR= r;
minP= p;
edgeFound = true;
}
}
}
}
//if edge was found add it to the tree
if(edgeFound)
{
g.mark(minR,minP);
g.mark(minP, minR);
g.mark(minP);
}
}
}
}
//add marked edges to spanning forest graph
for(int i=0; i<g.numNodes(); i++)
{
for(int j=i+1; j<g.numNodes(); j++)
{
if(g.isEdge(i,j) && g.isMarked(i,j))
{
sf.addEdge(i,j,g.getEdgeWeight(i,j));
sf.addEdge(j,i,g.getEdgeWeight(j,i));
cout<<"adding edge "<< i << " "<< j << endl;
cout<<"num edges: "<<sf.numEdges() << endl;
}
}
}
}
