public static Graph Kruskal(Graph inputGraph)
{
var result = new Graph();
result.Vertexes = inputGraph.Vertexes;
var edges = inputGraph.Edges.ToList();
edges.Sort();
var enumerator = edges.GetEnumerator();
var disjointSetUnion = new DisjointSetUnionTree(inputGraph.Vertexes);
while (result.Edges.Count < result.Vertexes.Count - 1) {
enumerator.MoveNext();
var edge = enumerator.Current;
var fromRoot = disjointSetUnion.Find(edge.From);
var toRoot = disjointSetUnion.Find(edge.To);
if (fromRoot != toRoot) {
disjointSetUnion.Union(edge.From, edge.To);
result.Edges.Add(edge);
}
}
return result;
}
public static Graph Boruvka(Graph graph)
{
var result = new Graph();
result.Vertexes = graph.Vertexes;
var disjointForest = new DisjointSetUnionTree(result.Vertexes);
while (result.Edges.Count < result.Vertexes.Count - 1) {
var safe = new Dictionary<int, Edge<int>>();
foreach (var edge in graph.Edges) {
var fromRoot = disjointForest.Find(edge.From);
var toRoot = disjointForest.Find(edge.To);
if (fromRoot != toRoot) {
if (!safe.ContainsKey(fromRoot) || edge.Weight < safe[fromRoot].Weight) {
safe[fromRoot] = edge;
}
if (!safe.ContainsKey(toRoot) || edge.Weight < safe[toRoot].Weight) {
safe[toRoot] = edge;
}
}
}
result.Edges.AddRange(safe.Values.Distinct());
foreach (var edge in safe.Values) {
disjointForest.Union(edge.From, edge.To);
}
}
return result;
}
public static int Cluster(Graph graph, int clusterCount)
{
var result = new Graph {
Vertexes = graph.Vertexes
};
var edges = graph.Edges.ToList();
edges.Sort();
var enumerator = edges.GetEnumerator();
var disjointSetUnion = new DisjointSetUnionTree(graph.Vertexes);
while (disjointSetUnion.Count != clusterCount - 1) {
enumerator.MoveNext();
var edge = enumerator.Current;
var fromRoot = disjointSetUnion.Find(edge.From);
var toRoot = disjointSetUnion.Find(edge.To);
if (fromRoot != toRoot) {
disjointSetUnion.Union(fromRoot, toRoot);
result.Edges.Add(edge);
}
}
return enumerator.Current.Weight;
}
public static Graph GenerateFullGraph(int vertexes, int weightFrom, int weightTo)
{
var result = new Graph();
for (var i = 0; i < vertexes; i++) {
result.Vertexes.Add(i);
}
for (var i = 0; i < vertexes; i++) {
for (var j = i + 1; j < vertexes; j++) {
var weight = random.Next(weightFrom, weightTo + 1);
result.Edges.Add(new Edge<int>(i, j, weight));
}
}
return result;
}
public static Graph NaivePrim(Graph inputGraph)
{
var result = new Graph();
result.Vertexes.Add(inputGraph.Vertexes.First());
while (result.Vertexes.Count != inputGraph.Vertexes.Count) {
var newEdge = inputGraph
.Edges
.Where(_ => result.Vertexes.Contains(_.From) ^ result.Vertexes.Contains(_.To))
.Min();
result.Edges.Add(newEdge);
result.Vertexes.Add(result.Vertexes.Contains(newEdge.From) ? newEdge.To : newEdge.From);
}
return result;
}
public static Graph GenerateFromFile(string path)
{
var reader = new StreamReader(path);
var firstLine = reader.ReadLine().Split(' ');
var vertexes = Convert.ToInt32(firstLine[0]);
var edges = Convert.ToInt32(firstLine[1]);
var graph = new Graph {
Vertexes = Enumerable.Range(0, vertexes).ToList()
};
for (var i = 0; i < edges; i++) {
var line = reader.ReadLine().Split(' ');
var from = Convert.ToInt32(line[0]) - 1;
var to = Convert.ToInt32(line[1]) - 1;
var weight = Convert.ToInt32(line[2]);
graph.Edges.Add(new Edge<int>(from, to, weight));
}
return graph;
}
public void Init()
{
inputGraph = new Graph();
inputGraph.Vertexes.Add(0);
inputGraph.Vertexes.Add(1);
inputGraph.Vertexes.Add(2);
inputGraph.Vertexes.Add(3);
inputGraph.Vertexes.Add(4);
inputGraph.Vertexes.Add(5);
inputGraph.Vertexes.Add(6);
inputGraph.Vertexes.Add(7);
inputGraph.Edges.Add(new Edge<int>(0, 1, 6));
inputGraph.Edges.Add(new Edge<int>(0, 2, 11));
inputGraph.Edges.Add(new Edge<int>(0, 3, 17));
inputGraph.Edges.Add(new Edge<int>(1, 2, 25));
inputGraph.Edges.Add(new Edge<int>(3, 2, 8));
inputGraph.Edges.Add(new Edge<int>(7, 2, 2));
inputGraph.Edges.Add(new Edge<int>(7, 5, 14));
inputGraph.Edges.Add(new Edge<int>(7, 6, 21));
inputGraph.Edges.Add(new Edge<int>(4, 5, 9));
inputGraph.Edges.Add(new Edge<int>(4, 1, 19));
}
public static Graph Kruskal(Graph inputGraph)
{
var result = new Graph();
result.Vertexes = inputGraph.Vertexes;
var edges = inputGraph.Edges.ToList();
edges.Sort(new WeightComparer<int>());
var disjointSetUnion = new DisjointSetUnionTree(inputGraph.Vertexes);
foreach (var edge in edges) {
var fromRoot = disjointSetUnion.Find(edge.From);
var toRoot = disjointSetUnion.Find(edge.To);
if (fromRoot != toRoot) {
disjointSetUnion.Union(fromRoot, toRoot);
result.Edges.Add(edge);
}
}
return result;
}
public static Graph GenerateTree(int vertexes)
{
var result = new Graph();
for (var i = 0; i < vertexes; i++) {
result.Vertexes.Add(i);
}
var disjointSet = new DisjointSetUnionTree(result.Vertexes);
while (result.Edges.Count < result.Vertexes.Count - 1) {
var from = random.Next(vertexes);
var to = random.Next(vertexes);
if (from == to || disjointSet.Find(from) == disjointSet.Find(to)) continue;
result.Edges.Add(new Edge<int>(from, to, 0));
disjointSet.Union(from, to);
}
return result;
}
private static void AssertSimpleSpanningTree(Graph graph)
{
Assert.AreEqual(8, graph.Vertexes.Count);
Assert.AreEqual(7, graph.Edges.Count);
Assert.AreEqual(71, graph.Weight);
}