public static SP GetSp(EdgeWeightedDigraph G, int s)
{
SP sp;
sp = new DijkstraSP(G, s);
return(sp);
}
private void Relax(EdgeWeightedDigraph G, int v)
{
foreach (var e in G.Adj(v))
{
var w = e.To();
if (_distTo[w] > _distTo[v] + e.Weight())
{
_distTo[w] = _distTo[v] + e.Weight();
_edgeTo[w] = e;
}
}
}
public DijkstraSP(EdgeWeightedDigraph G, int s) : base(G, s)
{
_pq = new IndexMinPQ <double>(G.E());
for (int i = 0; i < G.V(); i++)
{
_distTo[i] = double.PositiveInfinity;
}
_distTo[s] = 0d;
_pq.Insert(0, 0d);
while (!_pq.IsEmpty())
{
var w = _pq.RemoveMin();
Relax(G, w);
}
}
private void Relax(EdgeWeightedDigraph G, int v)
{
foreach (var e in G.Adj(v))
{
var w = e.To();
if (_distTo[w] > _distTo[v] + e.Weight())
{
_distTo[w] = _distTo[v] + e.Weight();
_edgeTo[w] = e;
if (_pq.Contains(w))
{
_pq.Change(w, _distTo[w]);
}
else
{
_pq.Insert(w, _distTo[w]);
}
}
}
}
public void RunSp()
{
EdgeWeightedDigraph G = new EdgeWeightedDigraph("tinyEWD.txt");
int s = 0;
SP sp = Factory.GetSp(G, s);
for (int t = 0; t < G.V(); t++)
{
Console.Write(s + " to " + t);
Console.Write(" ({0:F2}): ", sp.DistTo(t));
if (sp.HasPathTo(t))
{
foreach (DirectedEdge e in sp.PathTo(t))
{
Console.Write(e + " ");
}
}
Console.WriteLine();
}
}
