C++ graph::getEdgeWeight方法代码示例

edgepair getMinEdge(graph &g)
// iterate through whole graph and finds the edge from 
// marked node to unmarked node with minimum weight
// returns a struct with marked, unmarked, and weight
{
    int minCost = HIGH;
    int marked = NONE;
    int unmarked = NONE;
    
    // find the minimum edge
    for (int i = 0; i < g.numNodes() ; i++)
    {
        if (g.isMarked(i))
        {
            for (int j = 0; j < g.numNodes(); j++)
            {
                if (!g.isMarked(j) && g.isEdge(i, j) && g.getEdgeWeight(i, j) < minCost) 
                {
                    minCost = g.getEdgeWeight(i,j);
                    marked = i;
                    unmarked = j;
                }
            }
        }
    }

    edgepair pair = {marked, unmarked, minCost};
    return pair;
}

void findSpanningForest(graph &g, graph &sf)
	// Create a graph sf that contains a spanning forest on the graph g.
{
	if (isConnected(g) && !isCyclic(g))
	{
		sf = g;
	}
	else
	{
		// add nodes to sf
		for (int i = 0; i < g.numNodes(); i++)
		{
			sf.addNode(g.getNode(i));
		}

		// build sf
		for (int i = 0; i < g.numNodes(); i++)
		{
			for (int j = 0; j < g.numNodes(); j++)
			{
				if (g.isEdge(i, j) && !sf.isEdge(i, j))
				{
					sf.addEdge(i, j, g.getEdgeWeight(i, j));
					sf.addEdge(j, i, g.getEdgeWeight(j, i));

					if(isCyclic(sf))
					{
						sf.removeEdge(j, i);
						sf.removeEdge(i, j);
					} // if
				} // if
			} // for
		} // for
	} // else
} // findSpanningForest

void kruskal(graph &g, graph &sf)
// Given a weighted graph g, sets sf equal to a minimum spanning
// forest on g. Uses Kruskal's algorithm.
{
   g.clearMark();
   g.clearVisit();
   numComponents=0;
   while(!g.allNodesVisited())
   {
      // find the smallest edge
      int smallestEdgeWeight = -1;
      int smallestEdgeBeg = -1;
      int smallestEdgeEnd = -1;
      for(int i = 0; i < g.numNodes(); i++)
      {
         for(int j = 0; j < g.numNodes(); j++)
         {
            if(g.isEdge(i, j) && !g.isVisited(i, j) && !g.isVisited(j, i)
               && (!g.isVisited(i) || !g.isVisited(j)))
            {
               if(g.getEdgeWeight(i, j) < smallestEdgeWeight 
                  || smallestEdgeWeight == -1)
               {
                  smallestEdgeWeight = g.getEdgeWeight(i, j);
                  smallestEdgeBeg = i;
                  smallestEdgeEnd = j;
               }
            }
         }
      }
      // add the new edge
      g.visit(smallestEdgeBeg);
      g.visit(smallestEdgeEnd);
      g.visit(smallestEdgeBeg, smallestEdgeEnd);
      sf.addEdge(smallestEdgeBeg, smallestEdgeEnd);
      sf.setEdgeWeight(smallestEdgeBeg, smallestEdgeEnd, smallestEdgeWeight);
   }
   numComponents = getNumComponents(sf);
}

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.
{
   g.clearMark();
   g.clearVisit();
   numComponents=0;
   int currentNode = 0;
   while(!g.allNodesVisited())
   {
      // find next currentNode
      while(g.isVisited(currentNode) && currentNode < g.numNodes())
      {
         currentNode++;
      }
      g.visit(currentNode);
      int smallestEdgeWeight = -1;
      int smallestEdgeNode = -1;
      // find shortest new edge from currentNode
      for(int i = 0; i < g.numNodes(); i++)
      {
         if(g.isEdge(currentNode, i))
         {
            if(g.getEdgeWeight(currentNode, i) < smallestEdgeWeight 
               || smallestEdgeWeight == -1)
            {
               smallestEdgeWeight = g.getEdgeWeight(currentNode, i);
               smallestEdgeNode = i;
            }
         }
      }
      // add the new edge
      g.visit(smallestEdgeNode);
      sf.addEdge(currentNode, smallestEdgeNode);
      sf.setEdgeWeight(currentNode, smallestEdgeNode, smallestEdgeWeight);
   }
   numComponents = getNumComponents(sf);
}

void dfsAddEdges(graph &g, int current, graph &sf)
// depth first search to visit all nodes and add edges to unvisited nodes
{
    g.visit(current);
    vector<int> neighbors = getNeighbors(g, current);
    for (int i = 0; i < (int) neighbors.size(); i++)
    {
        if (!g.isVisited(neighbors[i]))
        {
            sf.addEdge(current, neighbors[i], g.getEdgeWeight(current, neighbors[i]));
            sf.addEdge(neighbors[i], current, g.getEdgeWeight(neighbors[i], current));
            dfsAddEdges(g, neighbors[i], sf);
        }
    }
}

void findSpanningForest(graph &g, graph &sf)
// Create a graph sf that contains a spanning forest on the graph g.
{
	queue<int> que;
	int id=0,count=1;
	bool first=true;
	vector<int> parentCount(g.numNodes(),-1);

	que.push(id);
	g.visit(id);

	while(count<g.numNodes() || !que.empty())
	{
		if (que.empty())
		{
			id=count;
			que.push(id);
			g.visit(id);
			count++;
		}
		else
			id=que.front();

		for(int i=0;i<g.numNodes();i++)
		{
			if (g.isEdge(id,i) && i!=que.front())
			{
				if(!g.isVisited(i) && parentCount[id]!=i)
				{
					g.visit(i);
					sf.addEdge(id,i,g.getEdgeWeight(i,id));
					sf.addEdge(i,id,g.getEdgeWeight(i,id));
					que.push(i);
					count++;
					parentCount[id]++;
				}
			}
		}
		que.pop();    
	}

	for (int z=0;z<g.numNodes();z++)
		g.unVisit(z);
}

pqueue getEdges(graph &g)
// iterate through graph and construct a priority queue with minimum cost
// only add an edgepair for edge between marked node and unmarked node
{
    pqueue edges;
    for (int i = 0; i < g.numNodes(); i++)
    {
        g.mark(i);
        
        for (int j = 0; j < g.numNodes(); j++)
        {
            if (g.isMarked(i) && !g.isMarked(j) && g.isEdge(i, j))
            {
                edgepair pair = {i, j, g.getEdgeWeight(i, j)};
                edges.push(pair);
            }
        }
    }
    return edges;
}

void findSpanningForest(graph &g, graph &sf)
// Create a graph sf that contains a spanning forest on the graph g.  
{
   g.clearMark();
   g.clearVisit();
   numComponents=0;
   queue<int> currentMoves;
   for (int n=0;n<g.numNodes();n++)
   {
      if (!g.isVisited(n))
      {  
         numComponents++;
         int nodeNumber=n;
         g.visit(nodeNumber);
         currentMoves.push(nodeNumber);
         while(currentMoves.size() > 0)
         {
            int currentNode = currentMoves.front();
            currentMoves.pop();
   
            //Populate a list of nodes that can be visited
            for (int i=0;i<g.numNodes();i++)
            {
               if (g.isEdge(currentNode,i) && !g.isVisited(i))
               {
                  g.mark(currentNode,i);
                  sf.addEdge(currentNode,i);
                  sf.setEdgeWeight(currentNode, i, g.getEdgeWeight(currentNode, i));
                  g.visit(i);
                  currentMoves.push(i);
               }
            }
         }
      }
   }
}

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;
			}
		}
	}
}