/// <summary>
/// Thanks to Morton Mertner for a fix here
/// </summary>
/// <param name="g"></param>
/// <param name="s"></param>
/// <returns></returns>
public static IDigraph DijkstrasAlgorithm(IDigraph g, int s)
{
int n = g.NumberOfVertices;
Entry[] table = new Entry[n];
for (int v = 0; v < n; ++v)
{
table[v] = new Entry(false,
int.MaxValue, int.MaxValue);
}
table[s].distance = 0;
IPriorityQueue queue = new BinaryHeap(g.NumberOfEdges);
queue.Enqueue(new Association(0, g.GetVertex(s)));
int vertexCount = 0; // MM fix
while (!queue.IsEmpty)
{
Association assoc = (Association)queue.DequeueMin();
IVertex v0 = (IVertex)assoc.Value;
if (!table[v0.Number].known)
{
table[v0.Number].known = true;
vertexCount++; // MM fix
foreach (IEdge e in v0.EmanatingEdges)
{
IVertex v1 = e.MateOf(v0);
int d = table[v0.Number].distance + (e.Weight != null ? (int)e.Weight : 0);
if (table[v1.Number].distance > d)
{
table[v1.Number].distance = d;
table[v1.Number].predecessor = v0.Number;
queue.Enqueue(new Association(d, v1));
}
}
}
}
// MM fixed loop to filter out unused edges and vertices
IDigraph result = new DigraphAsLists(vertexCount);
int cv = 0;
int[] v2cv = new int[n];
for (int v = 0; v < n; ++v)
{
if (table[v].known)
{
result.AddVertex(cv, table[v].distance);
v2cv[v] = cv++;
}
}
for (int v = 0; v < n; ++v)
{
if (v != s && table[v].known && table[v].distance < int.MaxValue)
{
result.AddConnection(v2cv[v], v2cv[table[v].predecessor]);
}
}
return(result);
}
/// <summary>
/// Critical path analysis algorithm
/// </summary>
/// <param name="g"></param>
/// <returns></returns>
public static IDigraph CriticalPathAnalysis(IDigraph g)
{
//TODO: more info here
int i = g.NumberOfVertices;
int[] nums1 = new int[(uint)i];
nums1[0] = 0;
g.TopologicalOrderTraversal(new EarliestTimeVisitor(nums1));
int[] nums2 = new int[(uint)i];
nums2[i - 1] = nums1[i - 1];
g.DepthFirstTraversal(new PostOrder(new LatestTimeVisitor(nums2)), 0);
IDigraph digraph1 = new DigraphAsLists(i);
for (int j = 0; j < i; j++)
{
digraph1.AddVertex(j);
}
IEnumerator iEnumerator = g.Edges.GetEnumerator();
try
{
while (iEnumerator.MoveNext())
{
IEdge edge = (IEdge)iEnumerator.Current;
int k = nums2[edge.V1.Number] - nums1[edge.V0.Number] - (int)edge.Weight;
digraph1.AddConnection(edge.V0.Number, edge.V1.Number, (int)edge.Weight);
}
}
finally
{
IDisposable iDisposable = iEnumerator as IDisposable;
if (iDisposable != null)
{
iDisposable.Dispose();
}
}
return(DijkstrasAlgorithm(digraph1, 0));
}
