//Алгоритм Прима
#region Prim()
public Graph Prim()
{
Graph graph = new Graph(this);
List <string> all_vertex = graph.GetListVertex();
Random rnd = new Random();
string random_vertex = all_vertex[rnd.Next(all_vertex.Count)];
Graph minimum_weight_frame = new Graph();
minimum_weight_frame.AddVertex(random_vertex);
all_vertex.Remove(random_vertex);
while (all_vertex.Count > 0)
{
List <Edge> adjacent = new List <Edge>();
List <string> proccessed_vertex = minimum_weight_frame.GetListVertex();
foreach (string vertex in proccessed_vertex)
{
foreach (KeyValuePair <string, double?> edge in graph.GetListWeightedEdges(vertex))
{
adjacent.Add(new Edge(vertex, edge.Key, edge.Value));
}
}
//Находим минимальные ребра
var min_weight = adjacent.Min(elem => elem.Weight);
var all_min_elem =
adjacent.Where(elem => elem.Weight == min_weight).ToList();
int random_index = rnd.Next(all_min_elem.Count);
graph.RemoveOrientedEdge(
all_min_elem[random_index].VertexFrom,
all_min_elem[random_index].VertexTo
);
minimum_weight_frame.AddVertex(all_min_elem[random_index].VertexTo);
all_vertex.Remove(all_min_elem[random_index].VertexTo);
minimum_weight_frame.AddOrientedEdge(
all_min_elem[random_index].VertexFrom,
all_min_elem[random_index].VertexTo,
all_min_elem[random_index].Weight
);
}
return(minimum_weight_frame);
}
