public void TreeSortTest()
{
// arrange
AlgorithmBase <int> tree = new DataStructures.Tree <int>(items);
// act
tree.SortAndGetSpan();
// assert
for (int i = 0; i < items.Count; i++)
{
Assert.AreEqual(sorted[i], tree.Items[i]);
}
}
/// <summary>
/// Returns a spanning tree rooted at given node to find a shortest path from any node to the root node.
/// </summary>
public DataStructures.Tree <Node <TNodeValue, TLinkProperty> > AnyShortestPath(Node <TNodeValue, TLinkProperty> fromNode)
{
if (fromNode == null || fromNode.Graph != this)
{
throw new Exception("Arguments are incorrect");
}
var treeNodes = new Dictionary <Node <TNodeValue, TLinkProperty>, bool>();
var treeLinks = new Dictionary <Link <TNodeValue, TLinkProperty>, bool>();
var tree = new DataStructures.Tree <Node <TNodeValue, TLinkProperty> >(fromNode); //resulting spanning tree
if (NodesCount == 0)
{
return(tree);
}
treeNodes.Add(fromNode, false);
var candidateLinks = new Dictionary <Link <TNodeValue, TLinkProperty>, bool>();
foreach (var l in fromNode.Links)
{
if (!l.IsLoop)
{
candidateLinks.Add(l, false); // add all links of fromNode to list
}
}
foreach (var n in nodes)
{
n.Weight = 0; // reset weights of all nodes
}
while (true)
{
if (candidateLinks.Count == 0 || treeNodes.Count == NodesCount)
{
break; // all nodes are processed
}
// find a node not in the tree that has the smallest distance from starting node
double smallestWeight = 0;
Link <TNodeValue, TLinkProperty> closestLink = null;
Node <TNodeValue, TLinkProperty> closestNode = null;
foreach (var l in candidateLinks.Keys)
{
if (!candidateLinks[l])
{
Node <TNodeValue, TLinkProperty> nodeInTree, nodeOutTree = null;
if (treeNodes.ContainsKey(l.Node1))
{
nodeInTree = l.Node1;
nodeOutTree = l.Node2;
}
else
{
nodeInTree = l.Node2;
nodeOutTree = l.Node1;
}
double newWeight = nodeInTree.Weight + l.Weight;
if (closestLink == null || newWeight < smallestWeight)
{
closestLink = l;
closestNode = nodeOutTree;
smallestWeight = newWeight;
}
}
}
// if both nodes of the link are in the tree, mark the link as added
if (closestNode == null)
{
break;
}
if (treeNodes.ContainsKey(closestNode))
{
candidateLinks[closestLink] = true;
}
else
{
// add found node to the spanning tree, set its weight, add node's links that lead to a node not yet in the tree, to the candidate links
closestNode.Weight = smallestWeight;
treeNodes.Add(closestNode, false);
foreach (var l in closestNode.Links)
{
var nodeNotInTree = l.Node1 == closestNode ? l.Node2 : l.Node1;
if (!treeNodes.ContainsKey(nodeNotInTree) && !l.IsLoop && !candidateLinks.ContainsKey(l))
{
candidateLinks.Add(l, false);
}
}
var parent = tree.Root.FindNodeByValue(closestLink.Node1 == closestNode ? closestLink.Node2 : closestLink.Node1);
parent.AddChild(closestNode);
}
}
// check if all nodes have been added (the graph might not be connected)
if (treeNodes.Count != this.NodesCount)
{
if (GraphType == GraphType.Undirected)
{
throw new Exception("Graph is not connected");
}
else
{
throw new Exception("Not possible to follow all nodes");
}
}
return(tree);
}
