public void Init()
{
m_Parents = new VertexVertexDictionary();
m_DiscoverTimes = new VertexIntDictionary();
m_FinishTimes = new VertexIntDictionary();
m_Time = 0;
}
/// <summary>
///
/// </summary>
/// <param name="g"></param>
public StrongComponentsAlgorithm(IVertexListGraph g)
{
if (g == null)
{
throw new ArgumentNullException("g");
}
m_VisitedGraph = g;
m_Components = new VertexIntDictionary();
m_Roots = new VertexVertexDictionary();
m_DiscoverTimes = new VertexIntDictionary();
m_Stack = new Stack();
m_Count = 0;
m_DfsTime = 0;
}
/// <summary>
/// Construct a strong component algorithm
/// </summary>
/// <param name="g">graph to apply algorithm on</param>
/// <exception cref="ArgumentNullException">graph is null</exception>
public StrongComponentsAlgorithm(IVertexListGraph g)
{
if (g == null)
{
throw new ArgumentNullException("g");
}
this.visitedGraph = g;
this.components = new VertexIntDictionary();
this.roots = new VertexVertexDictionary();
this.discoverTimes = new VertexIntDictionary();
this.stack = new Stack();
this.count = 0;
this.dfsTime = 0;
}
/// <summary>
/// Builds a new Bellman Ford searcher.
/// </summary>
/// <param name="g">The graph</param>
/// <param name="weights">Edge weights</param>
/// <exception cref="ArgumentNullException">Any argument is null</exception>
/// <remarks>This algorithm uses the <seealso cref="BreadthFirstSearchAlgorithm"/>.</remarks>
public BellmanFordShortestPathAlgorithm(
IVertexAndEdgeListGraph g,
EdgeDoubleDictionary weights
)
{
if (weights == null)
{
throw new ArgumentNullException("Weights");
}
m_VisitedGraph = g;
m_Colors = new VertexColorDictionary();
m_Weights = weights;
m_Distances = new VertexDoubleDictionary();
m_Predecessors = new VertexVertexDictionary();
}
public void Init()
{
parents = new VertexVertexDictionary();
discoverTimes = new VertexIntDictionary();
finishTimes = new VertexIntDictionary();
time = 0;
g = new BidirectionalGraph(true);
dfs = new UndirectedDepthFirstSearchAlgorithm(g);
dfs.StartVertex += new VertexEventHandler(this.StartVertex);
dfs.DiscoverVertex += new VertexEventHandler(this.DiscoverVertex);
dfs.ExamineEdge += new EdgeEventHandler(this.ExamineEdge);
dfs.TreeEdge += new EdgeEventHandler(this.TreeEdge);
dfs.BackEdge += new EdgeEventHandler(this.BackEdge);
dfs.FinishVertex += new VertexEventHandler(this.FinishVertex);
}
public void Init()
{
parents = new VertexVertexDictionary();
discoverTimes = new VertexIntDictionary();
finishTimes = new VertexIntDictionary();
time = 0;
g = new AdjacencyGraph(true);
dfs = new DepthFirstSearchAlgorithm(g);
dfs.StartVertex += new VertexEventHandler(this.StartVertex);
dfs.DiscoverVertex += new VertexEventHandler(this.DiscoverVertex);
dfs.ExamineEdge += new EdgeEventHandler(this.ExamineEdge);
dfs.TreeEdge += new EdgeEventHandler(this.TreeEdge);
dfs.BackEdge += new EdgeEventHandler(this.BackEdge);
dfs.ForwardOrCrossEdge += new EdgeEventHandler(this.FowardOrCrossEdge);
dfs.FinishVertex += new VertexEventHandler(this.FinishVertex);
}
/// <summary>
/// Checks if the child vertex is a child of the parent vertex
/// using the predecessor map.
/// </summary>
/// <param name="parent"></param>
/// <param name="child"></param>
/// <param name="predecessors"></param>
/// <returns></returns>
public static bool IsChild(
IVertex parent,
IVertex child,
VertexVertexDictionary predecessors
)
{
Object o = predecessors[child];
if (o == null || o == child) // child is the root of the tree
{
return(false);
}
else if (o == parent)
{
return(true);
}
else
{
return(IsChild(parent, (IVertex)o, predecessors));
}
}
/// <summary>
/// Builds a new Dijsktra searcher.
/// </summary>
/// <param name="g">The graph</param>
/// <param name="weights">Edge weights</param>
/// <exception cref="ArgumentNullException">Any argument is null</exception>
/// <remarks>This algorithm uses the <seealso cref="BreadthFirstSearchAlgorithm"/>.</remarks>
public DijkstraShortestPathAlgorithm(
IVertexListGraph g,
EdgeDoubleDictionary weights
)
{
if (g == null)
{
throw new ArgumentNullException("g");
}
if (weights == null)
{
throw new ArgumentNullException("Weights");
}
m_VisitedGraph = g;
m_Colors = new VertexColorDictionary();
m_Distances = new VertexDoubleDictionary();
m_Predecessors = new VertexVertexDictionary();
m_Weights = weights;
m_VertexQueue = null;
}
/// <summary>
/// Clones the <paramref name="source"/> to <paramref name="target"/> and
/// reverses the edges.
/// </summary>
/// <remarks>
/// <para>
/// Use this class to create clone of different graphs with possible different
/// provider types.
/// </para>
/// <para>
/// The <see cref="CloneVertex"/> and <see cref="CloneEdge"/> events can be
/// used to copy the custom properties
/// attached to each vertex and edge.
/// </para>
/// </remarks>
public void ReversedClone(IVertexAndEdgeListGraph source, IEdgeMutableGraph target)
{
VertexVertexDictionary vertexMap = new VertexVertexDictionary();
// copy vertices
foreach (IVertex v in source.Vertices)
{
IVertex vc = target.AddVertex();
// clone properties
OnCloneVertex(v, vc);
// store in table
vertexMap[v] = vc;
}
// copy edges
foreach (IEdge e in source.Edges)
{
IEdge ec = target.AddEdge(vertexMap[e.Target], vertexMap[e.Source]);
// cone properties
OnCloneEdge(e, ec);
}
}
/// <summary>
/// Compute the transitive closure and store it in the supplied graph 'tc'
/// </summary>
/// <param name="tc">
/// Mutable Graph instance to store the transitive closure
/// </param>
/// <exception cref="ArgumentNullException">
/// <paramref name="tc"/> is a <null/>.
/// </exception>
public void Create(IMutableVertexAndEdgeListGraph tc)
{
if (tc == null)
{
throw new ArgumentNullException("tc");
}
CondensationGraphAlgorithm cgalgo = new CondensationGraphAlgorithm(VisitedGraph);
cgalgo.Create(cg);
ArrayList topo_order = new ArrayList(cg.VerticesCount);
TopologicalSortAlgorithm topo = new TopologicalSortAlgorithm(cg, topo_order);
topo.Compute();
VertexIntDictionary in_a_chain = new VertexIntDictionary();
VertexIntDictionary topo_number = new VertexIntDictionary();
for (int order = 0; order < topo_order.Count; order++)
{
IVertex v = (IVertex)topo_order[order];
topo_number.Add(v, order);
if (!in_a_chain.Contains(v)) // Initially no vertex is present in a chain
{
in_a_chain.Add(v, 0);
}
}
VertexListMatrix chains = new VertexListMatrix();
int position = -1;
foreach (IVertex v in topo_order)
{
if (in_a_chain[v] == 0)
{
// Start a new chain
position = chains.AddRow();
IVertex next = v;
for (;;)
{
chains[position].Add(next);
in_a_chain[next] = 1;
// Get adjacent vertices ordered by topological number
// Extend the chain by choosing the adj vertex with lowest topo#
ArrayList adj = TopoSortAdjVertices(next, cg, topo_number);
if ((next = FirstNotInChain(adj, in_a_chain)) == null)
{
break;
}
}
}
}
VertexIntDictionary chain_number = new VertexIntDictionary();
VertexIntDictionary pos_in_chain = new VertexIntDictionary();
// Record chain positions of vertices
SetChainPositions(chains, chain_number, pos_in_chain);
VertexListMatrix successors = new VertexListMatrix();
successors.CreateObjectMatrix(cg.VerticesCount, chains.RowCount, int.MaxValue);
if (topo_order.Count > 0)
{
for (int rtopo = topo_order.Count - 1; rtopo > -1; rtopo--)
{
IVertex u = (IVertex)topo_order[rtopo];
foreach (IVertex v in TopoSortAdjVertices(u, cg, topo_number))
{
if (topo_number[v] < (int)successors[u.ID][chain_number[v]])
{
// {succ(u)} = {succ(u)} U {succ(v)}
LeftUnion(successors[u.ID], successors[v.ID]);
// {succ(u)} = {succ(u)} U {v}
successors[u.ID][chain_number[v]] = topo_number[v];
}
}
}
}
// Create transitive closure of condensation graph
// Remove existing edges in CG & rebuild edges for TC from
// successor set (to avoid duplicating parallel edges)
ArrayList edges = new ArrayList();
foreach (IEdge e in cg.Edges)
{
edges.Add(e);
}
foreach (IEdge e in edges)
{
cg.RemoveEdge(e);
}
foreach (IVertex u in cg.Vertices)
{
int i = u.ID;
for (int j = 0; j < chains.RowCount; j++)
{
int tnumber = (int)successors[i][j];
if (tnumber < int.MaxValue)
{
IVertex v = (IVertex)topo_order[tnumber];
for (int k = pos_in_chain[v]; k < chains[j].Count; k++)
{
cg.AddEdge(u, (IVertex)chains[j][k]);
}
}
}
}
// Maps a vertex in input graph to it's transitive closure graph
graphTransitiveClosures = new VertexVertexDictionary();
// Add vertices to transitive closure graph
foreach (IVertex v in visitedGraph.Vertices)
{
if (!graphTransitiveClosures.Contains(v))
{
IVertex vTransform = tc.AddVertex();
OnInitTransitiveClosureVertex(
new TransitiveClosureVertexEventArgs(
v, vTransform)
);
// Fire the TC Vertex Event
graphTransitiveClosures.Add(v, vTransform);
}
}
//Add edges connecting vertices within SCC & adjacent
// SCC (strongly connected component)
IVertexCollection scc_vertices = null;
foreach (IVertex s_tccg in cg.Vertices)
{
scc_vertices = (IVertexCollection)cgalgo.SCCVerticesMap[s_tccg.ID];
if (scc_vertices.Count > 1)
{
foreach (IVertex u in scc_vertices)
{
foreach (IVertex v in scc_vertices)
{
OnExamineEdge(tc.AddEdge(graphTransitiveClosures[u], graphTransitiveClosures[v]));
}
}
}
foreach (IEdge adj_edge in cg.OutEdges(s_tccg))
{
IVertex t_tccg = adj_edge.Target;
foreach (IVertex s in (IVertexCollection)cgalgo.SCCVerticesMap[s_tccg.ID])
{
foreach (IVertex t in (IVertexCollection)cgalgo.SCCVerticesMap[t_tccg.ID])
{
OnExamineEdge(tc.AddEdge(graphTransitiveClosures[s], graphTransitiveClosures[t]));
}
}
}
}
}
public void Init()
{
m_Parents = new VertexVertexDictionary();
m_Distances = new VertexIntDictionary();
}
//=======================================================================
// remove excess flow, the "second phase"
// This does a DFS on the reverse flow graph of nodes with excess flow.
// If a cycle is found, cancel it. Unfortunately it seems that we can't
// easily take advantage of DepthFirstSearchAlgorithm
// Return the nodes with excess flow in topological order.
//
// Unlike the prefl_to_flow() implementation, we use
// "color" instead of "distance" for the DFS labels
// "parent" instead of nl_prev for the DFS tree
// "topo_next" instead of nl_next for the topological ordering
private void ConvertPreflowToFlow()
{
IVertex r, restart, u;
IVertex bos = null, tos = null;
VertexVertexDictionary parents = new VertexVertexDictionary();
VertexVertexDictionary topoNext = new VertexVertexDictionary();
foreach (IVertex v in VisitedGraph.Vertices)
{
//Handle self-loops
foreach (IEdge a in VisitedGraph.OutEdges(v))
{
if (a.Target == v)
{
ResidualCapacities[a] = Capacities[a];
}
}
//Initialize
Colors[v] = GraphColor.White;
parents[v] = v;
current[v] = 0;
}
// eliminate flow cycles and topologically order the vertices
IVertexEnumerator vertices = VisitedGraph.Vertices.GetEnumerator();
while (vertices.MoveNext())
{
u = vertices.Current;
if (Colors[u] == GraphColor.White &&
excessFlow[u] > 0 &&
u != src && u != sink)
{
r = u;
Colors[r] = GraphColor.Gray;
while (true)
{
for (; current[u] < VisitedGraph.OutDegree(u); ++current[u])
{
IEdge a = VisitedGraph.OutEdges(u)[current[u]];
if (Capacities[a] == 0 && IsResidualEdge(a))
{
IVertex v = a.Target;
if (Colors[v] == GraphColor.White)
{
Colors[v] = GraphColor.Gray;
parents[v] = u;
u = v;
break;
}
else if (Colors[v] == GraphColor.Gray)
{
//find minimum flow on the cycle
double delta = ResidualCapacities[a];
while (true)
{
IEdge e = VisitedGraph.OutEdges(v)[current[v]];
delta = Math.Min(delta, ResidualCapacities[e]);
if (v == u)
{
break;
}
else
{
v = e.Target;
}
}
//remove delta flow units
v = u;
while (true)
{
a = VisitedGraph.OutEdges(v)[current[v]];
ResidualCapacities[a] -= delta;
ResidualCapacities[ReversedEdges[a]] += delta;
v = a.Target;
if (v == u)
{
break;
}
}
// back-out of DFS to the first saturated edge
restart = u;
for (v = VisitedGraph.OutEdges(u)[current[u]].Target;
v != u; v = a.Target)
{
a = VisitedGraph.OutEdges(v)[current[v]];
if (Colors[v] == GraphColor.White ||
IsSaturated(a))
{
Colors[VisitedGraph.OutEdges(v)[current[v]].Target] = GraphColor.White;
if (Colors[v] != GraphColor.White)
{
restart = v;
}
}
}
if (restart != u)
{
u = restart;
++current[u];
break;
}
}
}
}
if (current[u] == VisitedGraph.OutDegree(u))
{
// scan of i is complete
Colors[u] = GraphColor.Black;
if (u != src)
{
if (bos == null)
{
bos = u;
tos = u;
}
else
{
topoNext[u] = tos;
tos = u;
}
}
if (u != r)
{
u = parents[u];
++current[u];
}
else
{
break;
}
}
}
}
}
// return excess flows
// note that the sink is not on the stack
if (bos != null)
{
IEdgeEnumerator ai;
for (u = tos; u != bos; u = topoNext[u])
{
ai = VisitedGraph.OutEdges(u).GetEnumerator();
while (excessFlow[u] > 0 && ai.MoveNext())
{
if (Capacities[ai.Current] == 0 && IsResidualEdge(ai.Current))
{
PushFlow(ai.Current);
}
}
}
// do the bottom
u = bos;
ai = VisitedGraph.OutEdges(u).GetEnumerator();
while (excessFlow[u] > 0 && ai.MoveNext())
{
if (Capacities[ai.Current] == 0 && IsResidualEdge(ai.Current))
{
PushFlow(ai.Current);
}
}
}
}