public void FindSet()
{
FindSetTest(1, 2);
FindSetTest(
new TestVertex("1"),
new TestVertex("2"));
FindSetTest(
new EquatableTestVertex("1"),
new EquatableTestVertex("2"));
#region Local function
void FindSetTest <TValue>(TValue value1, TValue value2)
{
var set = new ForestDisjointSet <TValue>();
AssertSetSizes(set, 0, 0);
set.MakeSet(value1);
AssertSetSizes(set, 1, 1);
AssertEqual(value1, set.FindSet(value1));
set.MakeSet(value2);
AssertSetSizes(set, 2, 2);
AssertEqual(value1, set.FindSet(value1));
AssertEqual(value2, set.FindSet(value2));
set.Union(value1, value2);
AssertSetSizes(set, 1, 2);
AssertEqual(value1, set.FindSet(value1));
AssertEqual(value1, set.FindSet(value2));
}
#endregion
}
public void FindSet_Throws()
{
var vertex = new TestVertex();
var set = new ForestDisjointSet <TestVertex>();
// ReSharper disable ReturnValueOfPureMethodIsNotUsed
// ReSharper disable once AssignNullToNotNullAttribute
Assert.Throws <ArgumentNullException>(() => set.FindSet(null));
Assert.Throws <KeyNotFoundException>(() => set.FindSet(vertex));
// ReSharper restore ReturnValueOfPureMethodIsNotUsed
}
/// <summary>
/// Gets a copy of the connected components. Key is the number of components,
/// Value contains the vertex -> component index map.
/// </summary>
/// <returns>Number of components associated to components vertex mapping.</returns>
public KeyValuePair <int, IDictionary <TVertex, int> > GetComponents()
{
if (_sets is null)
{
throw new InvalidOperationException("Run the algorithm before.");
}
var representatives = new Dictionary <TVertex, int>(_sets.SetCount);
if (_components is null)
{
_components = new Dictionary <TVertex, int>(VisitedGraph.VertexCount);
}
foreach (TVertex vertex in VisitedGraph.Vertices)
{
TVertex representative = _sets.FindSet(vertex);
// ReSharper disable once AssignNullToNotNullAttribute, Justification: All graph vertices are in a set
if (!representatives.TryGetValue(representative, out int index))
{
representatives[representative] = index = representatives.Count;
}
_components[vertex] = index;
}
Debug.Assert(_sets.SetCount == ComponentCount);
Debug.Assert(_components.Count == VisitedGraph.VertexCount);
return(new KeyValuePair <int, IDictionary <TVertex, int> >(_sets.SetCount, _components));
}
/// <inheritdoc />
protected override void InternalCompute()
{
if (!TryGetRootVertex(out TVertex root))
{
throw new InvalidOperationException("Root vertex not set.");
}
if (_pairs is null)
{
throw new InvalidProgramException("Pairs not set.");
}
var graph = _pairs.ToAdjacencyGraph();
var disjointSet = new ForestDisjointSet <TVertex>();
var verticesAncestors = new Dictionary <TVertex, TVertex>();
var dfs = new DepthFirstSearchAlgorithm <TVertex, TEdge>(
this,
VisitedGraph,
new Dictionary <TVertex, GraphColor>(VisitedGraph.VertexCount));
dfs.InitializeVertex += vertex => disjointSet.MakeSet(vertex);
dfs.DiscoverVertex += vertex => verticesAncestors[vertex] = vertex;
dfs.TreeEdge += edge =>
{
disjointSet.Union(edge.Source, edge.Target);
// ReSharper disable once AssignNullToNotNullAttribute
// Justification: must be in the set because unioned just before.
verticesAncestors[disjointSet.FindSet(edge.Source)] = edge.Source;
};
dfs.FinishVertex += vertex =>
{
foreach (SEquatableEdge <TVertex> edge in graph.OutEdges(vertex))
{
if (dfs.VerticesColors[edge.Target] == GraphColor.Black)
{
SEquatableEdge <TVertex> pair = edge.ToVertexPair();
// ReSharper disable once AssignNullToNotNullAttribute
// Justification: must be present in the set.
Ancestors[pair] = verticesAncestors[disjointSet.FindSet(edge.Target)];
}
}
};
// Run DFS
dfs.Compute(root);
}
protected override void InternalCompute()
{
var cancelManager = this.Services.CancelManager;
TVertex root;
if (!this.TryGetRootVertex(out root))
{
throw new InvalidOperationException("root vertex not set");
}
if (this.pairs == null)
{
throw new InvalidOperationException("pairs not set");
}
var gpair = GraphExtensions.ToAdjacencyGraph(this.pairs);
var disjointSet = new ForestDisjointSet <TVertex>();
var vancestors = new Dictionary <TVertex, TVertex>();
var dfs = new DepthFirstSearchAlgorithm <TVertex, TEdge>(this, this.VisitedGraph, new Dictionary <TVertex, GraphColor>(this.VisitedGraph.VertexCount));
dfs.InitializeVertex += v => disjointSet.MakeSet(v);
dfs.DiscoverVertex += v => vancestors[v] = v;
dfs.TreeEdge += edge =>
{
disjointSet.Union(edge.Source, edge.Target);
vancestors[disjointSet.FindSet(edge.Source)] = edge.Source;
};
dfs.FinishVertex += v =>
{
foreach (var e in gpair.OutEdges(v))
{
if (dfs.VertexColors[e.Target] == GraphColor.Black)
{
this.ancestors[EdgeExtensions.ToVertexPair <TVertex, SEquatableEdge <TVertex> >(e)] = vancestors[disjointSet.FindSet(e.Target)];
}
}
};
// go!
dfs.Compute(root);
}
