/// Reverts the solver to its initial state.
public void Clear()
{
Dictionary <Node, long> excess = new Dictionary <Node, long>();
foreach (var n in Graph.Nodes())
{
excess[n] = Supply(n);
}
Saturated = new HashSet <Arc>();
foreach (var arc in Graph.Arcs())
{
long f = LowerBound(arc);
long g = UpperBound(arc);
if (g < long.MaxValue)
{
Saturated.Add(arc);
}
long flow = Flow(arc);
excess[Graph.U(arc)] -= flow;
excess[Graph.V(arc)] += flow;
}
Potential = new Dictionary <Node, double>();
MyGraph = new Supergraph(Graph);
ArtificialNode = MyGraph.AddNode();
Potential[ArtificialNode] = 0;
ArtificialArcs = new HashSet <Arc>();
var artificialArcOf = new Dictionary <Node, Arc>();
foreach (var n in Graph.Nodes())
{
long e = excess[n];
Arc arc = e > 0 ? MyGraph.AddArc(n, ArtificialNode, Directedness.Directed) :
MyGraph.AddArc(ArtificialNode, n, Directedness.Directed);
Potential[n] = (e > 0 ? -1 : 1);
ArtificialArcs.Add(arc);
artificialArcOf[n] = arc;
}
Tree = new Dictionary <Arc, long>();
TreeSubgraph = new Subgraph(MyGraph);
TreeSubgraph.EnableAllArcs(false);
foreach (var kv in artificialArcOf)
{
Tree[kv.Value] = Math.Abs(excess[kv.Key]);
TreeSubgraph.Enable(kv.Value, true);
}
State = SimplexState.FirstPhase;
EnteringArcEnumerator = MyGraph.Arcs().GetEnumerator();
EnteringArcEnumerator.MoveNext();
}
public void Clear()
{
Dictionary <Node, long> dictionary = new Dictionary <Node, long>();
foreach (Node item in Graph.Nodes())
{
dictionary[item] = Supply(item);
}
Saturated = new HashSet <Arc>();
foreach (Arc item2 in Graph.Arcs(ArcFilter.All))
{
LowerBound(item2);
long num = UpperBound(item2);
if (num < 9223372036854775807L)
{
Saturated.Add(item2);
}
long num2 = Flow(item2);
Node key;
Dictionary <Node, long> dictionary2;
(dictionary2 = dictionary)[key = Graph.U(item2)] = dictionary2[key] - num2;
Node key2;
(dictionary2 = dictionary)[key2 = Graph.V(item2)] = dictionary2[key2] + num2;
}
Potential = new Dictionary <Node, double>();
MyGraph = new Supergraph(Graph);
ArtificialNode = MyGraph.AddNode();
Potential[ArtificialNode] = 0.0;
ArtificialArcs = new HashSet <Arc>();
Dictionary <Node, Arc> dictionary3 = new Dictionary <Node, Arc>();
foreach (Node item3 in Graph.Nodes())
{
long num3 = dictionary[item3];
Arc arc = (num3 <= 0) ? MyGraph.AddArc(ArtificialNode, item3, Directedness.Directed) : MyGraph.AddArc(item3, ArtificialNode, Directedness.Directed);
Potential[item3] = (double)((num3 <= 0) ? 1 : (-1));
ArtificialArcs.Add(arc);
dictionary3[item3] = arc;
}
Tree = new Dictionary <Arc, long>();
TreeSubgraph = new Subgraph(MyGraph);
TreeSubgraph.EnableAllArcs(false);
foreach (KeyValuePair <Node, Arc> item4 in dictionary3)
{
Tree[item4.Value] = Math.Abs(dictionary[item4.Key]);
TreeSubgraph.Enable(item4.Value, true);
}
State = SimplexState.FirstPhase;
EnteringArcEnumerator = MyGraph.Arcs(ArcFilter.All).GetEnumerator();
EnteringArcEnumerator.MoveNext();
}
private void Run()
{
// direct all edges from the red nodes to the blue nodes
RedirectedGraph redToBlue = new RedirectedGraph(Graph,
x => (IsRed(Graph.U(x)) ? RedirectedGraph.Direction.Forward : RedirectedGraph.Direction.Backward));
// add a source and a target to the graph and some edges
Supergraph flowGraph = new Supergraph(redToBlue);
Node source = flowGraph.AddNode();
Node target = flowGraph.AddNode();
foreach (var node in Graph.Nodes())
{
if (IsRed(node))
{
flowGraph.AddArc(source, node, Directedness.Directed);
}
else
{
flowGraph.AddArc(node, target, Directedness.Directed);
}
}
Arc reflow = flowGraph.AddArc(target, source, Directedness.Directed);
// run the network simplex
NetworkSimplex ns = new NetworkSimplex(flowGraph,
lowerBound: x => (x == reflow ? MinimumMatchingSize : 0),
upperBound: x => (x == reflow ? MaximumMatchingSize : 1),
cost: x => (Graph.HasArc(x) ? Cost(x) : 0));
ns.Run();
if (ns.State == SimplexState.Optimal)
{
var matching = new Matching(Graph);
foreach (var arc in ns.UpperBoundArcs.Concat
(ns.Forest.Where(kv => kv.Value == 1).Select(kv => kv.Key)))
{
if (Graph.HasArc(arc))
{
matching.Enable(arc, true);
}
}
Matching = matching;
}
}
private void Run()
{
RedirectedGraph graph = new RedirectedGraph(Graph, (Arc x) => (!IsRed(Graph.U(x))) ? RedirectedGraph.Direction.Backward : RedirectedGraph.Direction.Forward);
Supergraph supergraph = new Supergraph(graph);
Node node = supergraph.AddNode();
Node node2 = supergraph.AddNode();
foreach (Node item in Graph.Nodes())
{
if (IsRed(item))
{
supergraph.AddArc(node, item, Directedness.Directed);
}
else
{
supergraph.AddArc(item, node2, Directedness.Directed);
}
}
Arc reflow = supergraph.AddArc(node2, node, Directedness.Directed);
NetworkSimplex networkSimplex = new NetworkSimplex(supergraph, (Arc x) => (x == reflow) ? MinimumMatchingSize : 0, (Arc x) => (!(x == reflow)) ? 1 : MaximumMatchingSize, null, (Arc x) => (!Graph.HasArc(x)) ? 0.0 : Cost(x));
networkSimplex.Run();
if (networkSimplex.State == SimplexState.Optimal)
{
Matching matching = new Matching(Graph);
foreach (Arc item2 in networkSimplex.UpperBoundArcs.Concat(from kv in networkSimplex.Forest
where kv.Value == 1
select kv.Key))
{
if (Graph.HasArc(item2))
{
matching.Enable(item2, true);
}
}
Matching = matching;
}
}
public Preflow(IGraph graph, Func <Arc, double> capacity, Node source, Node target)
{
Graph = graph;
Capacity = capacity;
Source = source;
Target = target;
flow = new Dictionary <Arc, double>();
// calculate bottleneck capacity to get an upper bound for the flow value
Dijkstra dijkstra = new Dijkstra(Graph, a => - Capacity(a), DijkstraMode.Maximum);
dijkstra.AddSource(Source);
dijkstra.RunUntilFixed(Target);
double bottleneckCapacity = -dijkstra.GetDistance(Target);
if (double.IsPositiveInfinity(bottleneckCapacity))
{
// flow value is infinity
FlowSize = double.PositiveInfinity;
Error = 0;
for (Node n = Target, n2 = Node.Invalid; n != Source; n = n2)
{
Arc arc = dijkstra.GetParentArc(n);
flow[arc] = double.PositiveInfinity;
n2 = Graph.Other(arc, n);
}
}
else
{
// flow value is finite
if (double.IsNegativeInfinity(bottleneckCapacity))
{
bottleneckCapacity = 0; // Target is not accessible
}
U = Graph.ArcCount() * bottleneckCapacity;
// calculate other upper bounds for the flow
double USource = 0;
foreach (var arc in Graph.Arcs(Source, ArcFilter.Forward))
{
if (Graph.Other(arc, Source) != Source)
{
USource += Capacity(arc);
if (USource > U)
{
break;
}
}
}
U = Math.Min(U, USource);
double UTarget = 0;
foreach (var arc in Graph.Arcs(Target, ArcFilter.Backward))
{
if (Graph.Other(arc, Target) != Target)
{
UTarget += Capacity(arc);
if (UTarget > U)
{
break;
}
}
}
U = Math.Min(U, UTarget);
Supergraph sg = new Supergraph(Graph);
Node newSource = sg.AddNode();
artificialArc = sg.AddArc(newSource, Source, Directedness.Directed);
CapacityMultiplier = Utils.LargestPowerOfTwo(long.MaxValue / U);
if (CapacityMultiplier == 0)
{
CapacityMultiplier = 1;
}
var p = new IntegerPreflow(sg, IntegralCapacity, newSource, Target);
FlowSize = p.FlowSize / CapacityMultiplier;
Error = Graph.ArcCount() / CapacityMultiplier;
foreach (var kv in p.NonzeroArcs)
{
flow[kv.Key] = kv.Value / CapacityMultiplier;
}
}
}
public Preflow(IGraph graph, Func <Arc, double> capacity, Node source, Node target)
{
Graph = graph;
Capacity = capacity;
Source = source;
Target = target;
flow = new Dictionary <Arc, double>();
Dijkstra dijkstra = new Dijkstra(Graph, (Arc a) => 0.0 - Capacity(a), DijkstraMode.Maximum);
dijkstra.AddSource(Source);
dijkstra.RunUntilFixed(Target);
double num = 0.0 - dijkstra.GetDistance(Target);
if (double.IsPositiveInfinity(num))
{
FlowSize = double.PositiveInfinity;
Error = 0.0;
Node node = Target;
Node invalid = Node.Invalid;
while (node != Source)
{
Arc parentArc = dijkstra.GetParentArc(node);
flow[parentArc] = double.PositiveInfinity;
invalid = Graph.Other(parentArc, node);
node = invalid;
}
}
else
{
if (double.IsNegativeInfinity(num))
{
num = 0.0;
}
U = (double)Graph.ArcCount(ArcFilter.All) * num;
double num2 = 0.0;
foreach (Arc item in Graph.Arcs(Source, ArcFilter.Forward))
{
if (Graph.Other(item, Source) != Source)
{
num2 += Capacity(item);
if (num2 > U)
{
break;
}
}
}
U = Math.Min(U, num2);
double num3 = 0.0;
foreach (Arc item2 in Graph.Arcs(Target, ArcFilter.Backward))
{
if (Graph.Other(item2, Target) != Target)
{
num3 += Capacity(item2);
if (num3 > U)
{
break;
}
}
}
U = Math.Min(U, num3);
Supergraph supergraph = new Supergraph(Graph);
Node node2 = supergraph.AddNode();
artificialArc = supergraph.AddArc(node2, Source, Directedness.Directed);
CapacityMultiplier = Utils.LargestPowerOfTwo(9.2233720368547758E+18 / U);
if (CapacityMultiplier == 0.0)
{
CapacityMultiplier = 1.0;
}
IntegerPreflow integerPreflow = new IntegerPreflow(supergraph, IntegralCapacity, node2, Target);
FlowSize = (double)integerPreflow.FlowSize / CapacityMultiplier;
Error = (double)Graph.ArcCount(ArcFilter.All) / CapacityMultiplier;
foreach (KeyValuePair <Arc, long> nonzeroArc in integerPreflow.NonzeroArcs)
{
flow[nonzeroArc.Key] = (double)nonzeroArc.Value / CapacityMultiplier;
}
}
}
