public static bool RemoveEdgeFromGraph(UndirectedGraph <int, Edge <int> > originalGraph, Edge <int> edgeToRemove, out UndirectedGraph <int, Edge <int> > resultGraph)
{
var edgeComparer = new EdgeComparer();
var edges = new HashSet <Edge <int> >(originalGraph.Edges, edgeComparer);
bool isRemoved = edges.Remove(edgeToRemove);
if (!isRemoved)
{
resultGraph = originalGraph;
return(false);
}
else
{
resultGraph = GetGraphFromEdges(edges);
return(true);
}
}
private static List <Edge <int> > LiftingV3(List <Edge <int> > augmentingPath, List <Edge <int> > blossom, UndirectedGraph <int, Edge <int> > g, Edge <int> edgeBetweenTrees, int superVertex, List <Edge <int> > currentMatching)
{
var edgeComparer = new EdgeComparer();
var matchedVertices = GetAllVerticesForPath(currentMatching);
var matchedEdges = new HashSet <Edge <int> >(currentMatching, new EdgeComparer());
GetPathEnds(augmentingPath, out int firstVertex, out int lastVertex);
var superVertexEdges = new List <Edge <int> >();
foreach (var edge in augmentingPath)
{
if (edge.Source == superVertex || edge.Target == superVertex)
{
superVertexEdges.Add(edge);
}
}
if (superVertexEdges.Count > 2)
{
throw new ArgumentException("There can be max 2 edges adjacent to superVertex in augmenting path");
}
var superVertexUnmatchedEdge = superVertexEdges.FirstOrDefault(edge => !matchedEdges.Contains(edge));
var superVertexMatchedEdge = superVertexEdges.FirstOrDefault(edge => matchedEdges.Contains(edge));
if (superVertexEdges.Count == 2 && (superVertexMatchedEdge == null || superVertexUnmatchedEdge == null))
{
throw new ArgumentException("Super vertex edges found incorrectly");
}
if (superVertexEdges.Count == 1 && (superVertexMatchedEdge == null && superVertexUnmatchedEdge == null))
{
throw new ArgumentException("Super vertex edges found incorrectly");
}
var pathForMatchedEdge = new List <Edge <int> >();
var pathForUnmatchedEdge = new List <Edge <int> >();
var pathForBlossom = new List <Edge <int> >();
if (superVertexMatchedEdge != null)
{
int oppositeToSuperVertex1 = GetTargetVertex(superVertexMatchedEdge, superVertex);
if (oppositeToSuperVertex1 != firstVertex && oppositeToSuperVertex1 != lastVertex)
{
var augmentingPathGraph1 = GetGraphFromEdges(augmentingPath);
var edges = new HashSet <Edge <int> >(g.Edges, edgeComparer);
if (!edges.Contains(superVertexMatchedEdge))
{
throw new ArgumentException("Graph should contain matched Edge");
}
bool wasRemoved = RemoveEdgeFromGraph(augmentingPathGraph1, superVertexMatchedEdge, out augmentingPathGraph1);
//bool remove1 = augmentingPathGraph1.RemoveEdge(superVertexMatchedEdge);
//bool remove2 = augmentingPathGraph1.RemoveEdge(new Edge<int>(superVertexMatchedEdge.Target, superVertexMatchedEdge.Source));
if (!wasRemoved)
{
throw new ArgumentException("Edge was not removed");
}
bool pathFound = DFSSearch(firstVertex, oppositeToSuperVertex1, augmentingPathGraph1, out List <Edge <int> > path1);
if (pathFound)
{
pathForMatchedEdge = path1;
}
else
{
pathFound = DFSSearch(oppositeToSuperVertex1, lastVertex, augmentingPathGraph1, out List <Edge <int> > path2);
if (!pathFound)
{
throw new ArgumentException("Path should exist");
}
pathForMatchedEdge = path2;
}
}
pathForMatchedEdge.Add(superVertexMatchedEdge);
}
if (superVertexUnmatchedEdge != null)
{
int oppositeToSuperVertex2 = GetTargetVertex(superVertexUnmatchedEdge, superVertex);
if (oppositeToSuperVertex2 != firstVertex && oppositeToSuperVertex2 != lastVertex)
{
var augmentingPathGraph2 = GetGraphFromEdges(augmentingPath);
var edges = new HashSet <Edge <int> >(g.Edges, edgeComparer);
//if (!edges.Contains(superVertexUnmatchedEdge))
// throw new ArgumentException("Graph should contain matched Edge");
bool wasRemoved = RemoveEdgeFromGraph(augmentingPathGraph2, superVertexUnmatchedEdge, out augmentingPathGraph2);
//bool remove1 = augmentingPathGraph2.RemoveEdge(superVertexUnmatchedEdge);
//bool remove2 = augmentingPathGraph2.RemoveEdge(new Edge<int>(superVertexUnmatchedEdge.Target, superVertexUnmatchedEdge.Source));
if (!wasRemoved)
{
throw new ArgumentException("Edge was not removed");
}
bool pathFound = DFSSearch(firstVertex, oppositeToSuperVertex2, augmentingPathGraph2, out List <Edge <int> > path1);
if (pathFound)
{
pathForUnmatchedEdge = path1;
}
else
{
pathFound = DFSSearch(oppositeToSuperVertex2, lastVertex, augmentingPathGraph2, out List <Edge <int> > path2);
if (!pathFound)
{
throw new ArgumentException("Path should exist");
}
pathForUnmatchedEdge = path2;
}
}
//pathForUnmatchedEdge.Add(superVertexUnmatchedEdge);
}
Edge <int> firstEdgeInPath = null;
var blossomVertices = GetAllVerticesForPath(blossom);
int oppositeToSuperVertex = GetTargetVertex(superVertexUnmatchedEdge, superVertex);
int firstVertexOnBlossom = -1;
foreach (var edge in g.AdjacentEdges(oppositeToSuperVertex))
{
int target = GetTargetVertex(edge, oppositeToSuperVertex);
if (blossomVertices.Contains(target))
{
firstEdgeInPath = edge;
firstVertexOnBlossom = target;
break;
}
}
if (firstEdgeInPath == null || firstVertexOnBlossom < 0)
{
throw new ArgumentException("This path should be found");
}
if (!matchedVertices.Contains(firstVertexOnBlossom))
{
return(augmentingPath);
}
if (firstVertexOnBlossom == superVertex)
{
pathForBlossom = new List <Edge <int> > {
firstEdgeInPath
};
}
else
{
var blossomGraph = GetGraphFromEdges(blossom);
foreach (var edge in blossomGraph.AdjacentEdges(firstVertexOnBlossom))
{
int target = GetTargetVertex(edge, firstVertexOnBlossom);
if (!matchedVertices.Contains(target))
{
bool edgeRemoved = blossomGraph.RemoveEdge(edge);
if (!edgeRemoved)
{
throw new ArgumentException("Edge should be removed");
}
break;
}
}
bool pathFound = DFSSearch(firstVertexOnBlossom, superVertex, blossomGraph, out pathForBlossom);
pathForBlossom.Add(firstEdgeInPath);
}
// Merge results for all the 3 paths
var augmentingPathGraph = GetGraphFromEdges(pathForBlossom);
if (superVertexMatchedEdge != null)
{
augmentingPathGraph.AddVerticesAndEdgeRange(pathForMatchedEdge);
}
if (superVertexUnmatchedEdge != null)
{
augmentingPathGraph.AddVerticesAndEdgeRange(pathForUnmatchedEdge);
}
if (!augmentingPathGraph.Vertices.Contains(firstVertex) || !augmentingPathGraph.Vertices.Contains(lastVertex))
{
throw new ArgumentException("First and last vertex must be a part of the graph");
}
var liftedAugmentingPathFound = DFSSearch(firstVertex, lastVertex, augmentingPathGraph, out List <Edge <int> > liftedAugmentingPath);
if (!liftedAugmentingPathFound)
{
throw new ArgumentException("Lifted augmenting path not found");
}
return(liftedAugmentingPath);
}
