/// <summary>
/// Finds the shortest path between the specified nodes and returns it as a list of nodes.
/// </summary>
/// <param name="start">The starting node for the path</param>
/// <param name="end">The ending node for the path</param>
/// <returns>The path, represented as a list of nodes beginning with start and ending with end.</returns>
public List <Node> FindPath(Node start, Node end)
{
BinaryHeap path = new BinaryHeap(Nodes.Length);
foreach (Node n in Nodes)
{
n.NodeCost = double.PositiveInfinity;
n.Predecessor = null;
}
start.NodeCost = 0;
foreach (Node n in Nodes)
{
path.Add(n, n.NodeCost);
}
Node j, k;
double newCost;
while (path.Count != 0)
{
j = path.ExtractMin();
if (j == end)
{
List <Node> Path = new List <Node>();
while (j != null)
{
Path.Add(j);
j = j.Predecessor;
}
Path.Reverse();
return(Path);
}
foreach (UndirectedEdge e in j.Edges)
{
k = e.OtherNode(j);
newCost = j.NodeCost + e.Cost;
if (newCost < k.NodeCost)
{
path.DecreasePriority(k, newCost);
k.NodeCost = newCost;
k.Predecessor = j;
}
}
}
return(null);
}
/// <summary>
/// Finds the shortest path between the specified nodes and returns it as a list of nodes.
/// </summary>
/// <param name="start">The starting node for the path</param>
/// <param name="end">The ending node for the path</param>
/// <returns>The path, represented as a list of nodes beginning with start and ending with end.</returns>
public List <Node> FindPath(Node start, Node end)
{
BinaryHeap pq = new BinaryHeap(Nodes.Length);
foreach (Node n in Nodes)
{
if (n == start)
{
n.NodeCost = 0;
}
else
{
n.NodeCost = Double.PositiveInfinity;
}
n.Predecessor = null;
pq.Add(n, n.NodeCost);
}
while (pq.Count != 0)
{
Node n = pq.ExtractMin();
if (n == end)
{
break;
}
foreach (UndirectedEdge v in n.Edges)
{
Node temp;
if (v.A == n)
{
temp = v.B;
}
else
{
temp = v.A;
}
double w = v.Cost;
double newCost = w + n.NodeCost;
if (newCost < temp.NodeCost)
{
pq.DecreasePriority(temp, newCost);
temp.NodeCost = newCost;
temp.Predecessor = n;
}
}
}
Stack <Node> s = new Stack <Node>();
Node t = end;
s.Push(t);
while (t.Predecessor != null)
{
s.Push(t.Predecessor);
t = t.Predecessor;
}
List <Node> l = new List <Node>();
while (s.Count != 0)
{
l.Add(s.Pop());
}
return(l);
}