public Tuple <int, List <Node> > findShortestPath(string start, string end)
{
//New Dictionary that contains a the name of each node and corresponding shortest path length and node order
Dictionary <string, Tuple <int, List <Node> > > shortestPaths = new Dictionary <string, Tuple <int, List <Node> > >();
//List of remaining nodes
List <string> remainingNodes = new List <string>();
//Loop over nodes and add each node to remaining nodes and shortest path with initial values of -1
foreach (Node node in this.Nodes)
{
remainingNodes.Add(node.name);
shortestPaths[node.name] = new Tuple <int, List <Node> > (-1, new List <Node>());
}
//Set start node to path length of 0 and remove it from remaining nodes
shortestPaths[start] = new Tuple <int, List <Node> >(0, new List <Node>());
Node lastVisitedNode = getNodeByName(start);
remainingNodes.Remove(start);
List <Node> addNodeToPath(List <Node> oldPath, Node newNode)
{
//Create the new list of nodes on path
List <Node> newPath = new List <Node>();
foreach (Node node in oldPath)
{
newPath.Add(node);
}
//Add new node to list
newPath.Add(newNode);
return(newPath);
}
//Loop untill there are no remaining nodes
while (remainingNodes.Count > 0)
{
//Loop over the connected Nodes of the last node removed
foreach (KeyValuePair <string, int> node in lastVisitedNode.getConnectedNodes())
{
//calcuate the path length from its current shortest path + edge length
int path = shortestPaths[lastVisitedNode.name].Item1 + node.Value;
//Get the current shortest path to the node
int currentShortestPath = shortestPaths[node.Key].Item1;
//if the node as currentShortestPath of -1 it has not been visited yet
if (currentShortestPath == -1)
{
//Add node to path
List <Node> newPath = addNodeToPath(shortestPaths[lastVisitedNode.name].Item2, getNodeByName(node.Key));
//Update shortest Paths
shortestPaths[node.Key] = new Tuple <int, List <Node> >(path, newPath);
}
else if (path < shortestPaths[node.Key].Item1 && shortestPaths[node.Key].Item1 != -1)
{
//Add node to path
List <Node> newPath = addNodeToPath(shortestPaths[lastVisitedNode.name].Item2, getNodeByName(node.Key));
//Update shortest Paths
shortestPaths[node.Key] = new Tuple <int, List <Node> >(path, newPath);
}
}
//After updating all shortest paths of connected nodes, check for the shortest one
KeyValuePair <string, int> shortest = new KeyValuePair <string, int>("default", -1);
foreach (string nodeName in remainingNodes)
{
Node node = getNodeByName(nodeName);
//first nodes
if (shortest.Value == -1)
{
//update shortest
shortest = new KeyValuePair <string, int>(nodeName, shortestPaths[nodeName].Item1);
//check if the path to current node is shortest and make sure it has actually been visited
}
else if (shortestPaths[nodeName].Item1 < shortest.Value && shortestPaths[nodeName].Item1 != -1)
{
//update shortest
shortest = new KeyValuePair <string, int>(nodeName, shortestPaths[nodeName].Item1);
}
}
//Shortest path found
remainingNodes.Remove(shortest.Key);
//update last visited Node
lastVisitedNode = getNodeByName(shortest.Key);
}
//Shortest path to all nodes found
return(new Tuple <int, List <Node> >(shortestPaths[end].Item1, shortestPaths[end].Item2));
}
public Dictionary <string, int> getConnectedNodes(string target)
{
Node targetNode = getNodeByName(target);
return(targetNode.getConnectedNodes());
}
