/// <summary>
/// Generates all the possible edges for given nodes and returns them.
/// </summary>
/// <param name="listNodes">The list nodes.</param>
/// <param name="listEdges">[out]The list edges.</param>
/// <returns></returns>
public static bool generateEdgeList(SortedNodeList listNodes,
out SortedEdgeList listEdges)
{
bool bRet = false;
SortedEdgeList l_listEdges = new SortedEdgeList();
UInt32 nEdgeID = 0;
for(Int32 nFrom = 0; nFrom < listNodes.Count; ++nFrom)
{
for (Int32 nTo = nFrom+1; nTo < listNodes.Count; ++nTo)
{
// make sure it is sorted by distance.
GraphEdge e = new GraphEdge(++nEdgeID,
listNodes[nFrom],
listNodes[nTo],
0);
l_listEdges.AddSorted(e);
bRet = true;
}
}
listEdges = l_listEdges;
return bRet;
}
/// <summary>
/// Runs the KRUSKAL algorithm. It takes parameters from the graph.
/// it applies the KRUSKAL algorithm on the edges and finally stores
/// the Minimal list of edges in the graph so that it becomes a tree.
/// I have preferred to use Graph data structres over tree, It allows
/// me to store more data than tree.
/// </summary>
/// <param name="listEdges">list of KRUSKAL Edges.</param>
/// <returns></returns>
public bool runKruskal(out SortedEdgeList listEdges)
{
bool bRet = false;
// 1. an empty list of edges, this shall be filled.
SortedEdgeList l_listEdges = new SortedEdgeList();
// we already have sorted list, our DataStruct handles it.
// we want to update our edges link in graphnodes hence cleaning
// existing links.
foreach (GraphNode n in m_listNodes)
{
n.m_listEdge.Clear();
}
// 2 lets generate all possible list of edges (n!)
SortedEdgeList l_AllPossibleEdges = new SortedEdgeList();
Util.generateEdgeList(m_listNodes, out l_AllPossibleEdges);
// 3. foreach edge @ graph (existing links)
foreach (GraphEdge e in l_AllPossibleEdges)
{
// check if it connects two nodes. do a DFS search.
// essentially this shall choose smallest edges first.
// each of node contains edges. so hasPathDFS() checks for any
// feasible path between those edges.
// if no path exists, than this link connects them
// so I am adding it.
if (Util.hasPathDFS(e.m_nodeFrom, e.m_nodeTo) == false)
{
// add the edge in the list
l_listEdges.AddSorted(e);
// add edges in from and to
e.m_nodeFrom.addEdge(e);
e.m_nodeTo.addEdge(e);
bRet = true;
}
}
// 4. assign it to out parameter
listEdges = l_listEdges;
return bRet;
}