public void BiDirectional_Smoke_Test()
{
var graph = new DiGraph <char>();
graph.AddVertex('A');
graph.AddVertex('B');
graph.AddVertex('C');
graph.AddVertex('D');
graph.AddVertex('E');
graph.AddVertex('F');
graph.AddVertex('G');
graph.AddVertex('H');
graph.AddVertex('I');
graph.AddEdge('A', 'B');
graph.AddEdge('B', 'C');
graph.AddEdge('C', 'D');
graph.AddEdge('D', 'E');
graph.AddEdge('E', 'F');
graph.AddEdge('F', 'G');
graph.AddEdge('G', 'H');
graph.AddEdge('H', 'I');
var algorithm = new BiDirectional <char>();
Assert.IsTrue(algorithm.PathExists(graph, 'A', 'I'));
graph.RemoveEdge('D', 'E');
graph.AddEdge('E', 'D');
Assert.IsFalse(algorithm.PathExists(graph, 'A', 'I'));
}
public void DiGraph_Smoke_Test()
{
var graph = new DiGraph <int>();
graph.AddVertex(1);
graph.AddVertex(2);
graph.AddVertex(3);
graph.AddVertex(4);
graph.AddVertex(5);
graph.AddEdge(1, 2);
Assert.IsTrue(graph.HasEdge(1, 2));
Assert.IsFalse(graph.HasEdge(2, 1));
graph.AddEdge(3, 2);
Assert.AreEqual(2, graph.InEdges(2).Count());
graph.RemoveEdge(3, 2);
graph.AddEdge(2, 3);
graph.AddEdge(3, 4);
graph.AddEdge(4, 5);
graph.AddEdge(4, 1);
graph.AddEdge(3, 5);
Assert.AreEqual(2, graph.OutEdges(4).Count());
Assert.AreEqual(5, graph.VerticesCount);
Assert.IsTrue(graph.HasEdge(1, 2));
graph.RemoveEdge(1, 2);
Assert.IsFalse(graph.HasEdge(1, 2));
graph.RemoveEdge(2, 3);
graph.RemoveEdge(3, 4);
graph.RemoveEdge(4, 5);
graph.RemoveEdge(4, 1);
Assert.IsTrue(graph.HasEdge(3, 5));
graph.RemoveEdge(3, 5);
Assert.IsFalse(graph.HasEdge(3, 5));
graph.RemoveVertex(1);
graph.RemoveVertex(2);
graph.RemoveVertex(3);
graph.AddEdge(4, 5);
graph.RemoveVertex(4);
graph.AddEdge(5, 5);
graph.RemoveEdge(5, 5);
graph.RemoveVertex(5);
Assert.AreEqual(0, graph.VerticesCount);
}
/// <summary>
/// Breaks cycles in the graph, returning all edges that changed their orientation.
/// </summary>
/// <param name="graph"></param>
/// <returns></returns>
public List <(Operation Operation1, Operation Operation2)> BreakCycles(DiGraph <Operation> graph)
{
var changedOrientationEdges = new List <(Operation Operation1, Operation Operation2)>();
var algorithm = new TarjansStronglyConnected <Operation>();
List <List <Operation> > components;
do
{
// find strongly connected components
components = algorithm.FindStronglyConnectedComponents(graph).Where(x => x.Count > 1).ToList();
foreach (List <Operation> component in components.AsShuffledEnumerable())
{
var componentHashSet = component.ToHashSet();
foreach (var operation1 in component.AsShuffledEnumerable())
{
// get all neighbor operations that are in the same component
var neighborOperations = GetNeighborComponentOperations(graph, operation1, componentHashSet);
foreach (var operation2 in neighborOperations.AsShuffledEnumerable())
{
// two operations are not on the same job
// but are on the same machines (=> can switch their edge orientation if I need to)
if (operation1.JobId != operation2.JobId &&
operation1.MachineId == operation2.MachineId)
{
double probability = RandomizationProvider.Current.GetDouble();
// switch directions of edge with prob for back edge, forward edge or same level edge
if ((operation1.Order > operation2.Order && probability <= backEdgeBreakProbability) ||
(operation1.Order < operation2.Order && probability <= forwardEdgeBreakProbability) ||
(operation1.Order == operation2.Order && probability <= sameLevelEdgeBreakProbability))
{
// switch edge orientation
graph.RemoveEdge(operation1, operation2);
graph.AddEdge(operation2, operation1);
changedOrientationEdges.Add((operation1, operation2));
goto cycleOut;
}
}
}
}
}
cycleOut :;
} while (components.Count > 0);
return(changedOrientationEdges);
}
public void Graph_Cycle_Detection_Tests()
{
var graph = new DiGraph <char>();
graph.AddVertex('A');
graph.AddVertex('B');
graph.AddVertex('C');
graph.AddVertex('D');
graph.AddVertex('E');
graph.AddVertex('F');
graph.AddVertex('G');
graph.AddVertex('H');
graph.AddEdge('A', 'B');
graph.AddEdge('B', 'C');
graph.AddEdge('C', 'A');
graph.AddEdge('C', 'D');
graph.AddEdge('D', 'E');
graph.AddEdge('E', 'F');
graph.AddEdge('F', 'G');
graph.AddEdge('G', 'E');
graph.AddEdge('F', 'H');
var algo = new CycleDetector <char>();
Assert.IsTrue(algo.HasCycle(graph));
graph.RemoveEdge('C', 'A');
graph.RemoveEdge('G', 'E');
Assert.IsFalse(algo.HasCycle(graph));
}
