static void Main(string[] args)
{
DisjointSets ds = new DisjointSets();
ds.MakeSet(1);
ds.MakeSet(2);
ds.MakeSet(3);
ds.MakeSet(4);
ds.MakeSet(5);
ds.MakeSet(6);
ds.MakeSet(7);
ds.Union(1, 2);
ds.Union(2, 3);
ds.Union(4, 5);
ds.Union(6, 7);
ds.Union(5, 6);
ds.Union(3, 7);
Console.WriteLine(ds.FindSet(1).Data);
Console.WriteLine(ds.FindSet(2).Data);
Console.WriteLine(ds.FindSet(3).Data);
Console.WriteLine(ds.FindSet(4).Data);
Console.WriteLine(ds.FindSet(5).Data);
Console.WriteLine(ds.FindSet(6).Data);
Console.WriteLine(ds.FindSet(7).Data);
}
public void MakeSet_WithPreExistingElements()
{
var sets = new DisjointSets <int>(Enumerable.Range(1, 10));
foreach (int i in Enumerable.Range(11, 10))
{
sets.MakeSet(i);
}
foreach (int i in Enumerable.Range(1, 20))
{
Assert.That(sets.FindSet(i), Is.EqualTo(i));
}
}
/// <summary>
///
/**https://en.wikipedia.org/wiki/Kruskal%27s_algorithm
* KRUSKAL(G):
* 1 A = ∅
* 2 foreach v ∈ G.V:
* 3 MAKE-SET(v)
* 4 foreach (u, v) in G.E ordered by weight(u, v), increasing:
* 5 if FIND-SET(u) ≠ FIND-SET(v):
* 6 A = A ∪ {(u, v)}
* 7 UNION(u, v)
* 8 return A
* **/
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="g"></param>
/// <returns></returns>
public static List <Edge <T> > GetMSTUsingKruskal <T>(this Graph <T> g)
{
EdgeComparer <T> comparer = new EdgeComparer <T>();
List <Edge <T> > result = new List <Edge <T> >();
//First sort the edges
g.AllEdges.Sort(comparer);
Console.WriteLine("Edes in Sorted Order");
foreach (var e in g.AllEdges)
{
Console.WriteLine(e.ToString());
}
DisjointSets disjointSet = new DisjointSets();
//Create Set for each vertex
foreach (var v in g.AllVertex.Values)
{
disjointSet.MakeSet(v.Id);
}
//For each edge, check if vertex is already in SET.
//1. If yes, ignore
//2. If not, Union and add it to result of edge
foreach (var e in g.AllEdges)
{
var n1 = disjointSet.FindSet(e.V1.Id);
var n2 = disjointSet.FindSet(e.V2.Id);
if (n1 == n2)
{
continue;
}
else
{
result.Add(e);
disjointSet.Union(e.V1.Id, e.V2.Id);
}
}
return(result);
}
public override void Run()
{
Result = new ConnectedComponentImage(InputImage.Width, InputImage.Height, -1);
var cursor = new ImageCursor(InputImage, 1); // per semplicità ignora i bordi (1 pixel)
int[] neighborLabels = new int[Metric == MetricType.CityBlock ? 2 : 4];
int nextLabel = 0;
var equivalences = new DisjointSets(InputImage.PixelCount);
do
{ // prima scansione
if (InputImage[cursor] == Foreground)
{
int labelCount = 0;
if (Result[cursor.West] >= 0)
{
neighborLabels[labelCount++] = Result[cursor.West];
}
if (Result[cursor.North] >= 0)
{
neighborLabels[labelCount++] = Result[cursor.North];
}
if (Metric == MetricType.Chessboard)
{ // anche le diagonali
if (Result[cursor.Northwest] >= 0)
{
neighborLabels[labelCount++] = Result[cursor.Northwest];
}
if (Result[cursor.Northeast] >= 0)
{
neighborLabels[labelCount++] = Result[cursor.Northeast];
}
}
if (labelCount == 0)
{
equivalences.MakeSet(nextLabel); // crea un nuovo set
Result[cursor] = nextLabel++; // le etichette iniziano da 0
}
else
{
int l = Result[cursor] = neighborLabels[0]; // seleziona la prima
for (int i = 1; i < labelCount; i++) // equivalenze
{
if (neighborLabels[i] != l)
{
equivalences.MakeUnion(neighborLabels[i], l); // le rende equivalenti
}
}
}
}
} while (cursor.MoveNext());
//rende le etichette numeri consecutivi
int totalLabels;
int[] corresp = equivalences.Renumber(nextLabel, out totalLabels);
//seconda e ultima scansione
cursor.Restart();
do
{
int l = Result[cursor];
if (l >= 0)
{
Result[cursor] = corresp[l];
}
}while(cursor.MoveNext());
Result.ComponentCount = totalLabels;
}