public string[] kruskal(int vertices, List <List <Edge> > adj)
{
string[] spanningTree = new string[vertices];
int itr = 0;
Dictionary <Edge, int> from = new Dictionary <Edge, int>();
PriorityQueue <Edge> queue = new PriorityQueue <Edge>();
for (int i = 0; i <= vertices; i++)
{
foreach (var edge in adj[i])
{
queue.push(edge);
from[edge] = i;
}
}
int[] parent = new int[vertices + 1];
for (int i = 1; i <= vertices; i++)
{
parent[i] = i;
}
while (!queue.empty)
{
Edge current = queue.pop();
if (Union(parent, from[current], current.v))
{
spanningTree[itr++] = from[current] + " " + current.ToString();
}
}
return(spanningTree);
}
public string[] prim(int vertices, List <List <Edge> > adj)
{
string[] spanningTree = new string[vertices];
int itr = 0;
bool[] picked = new bool[vertices + 1];
int start = 1;
picked[start] = true;
PriorityQueue <Edge> queue = new PriorityQueue <Edge>();
Dictionary <Edge, int> from = new Dictionary <Edge, int>();
foreach (var edge in adj[start])
{
queue.push(edge);
from[edge] = start;
}
while (!queue.empty)
{
Edge current = queue.pop();
if (picked[current.v])
{
continue;
}
picked[current.v] = true;
spanningTree[itr++] = from[current] + " " + current.ToString();
foreach (var edge in adj[current.v])
{
if (!picked[edge.v])
{
queue.push(edge);
from[edge] = current.v;
}
}
}
return(spanningTree);
}
/*-------------------Prims Algorithm------------------------------*/
public List <Edge <T> > MSTPrim()
{
int[] previous = new int[Nodes.Count]; // stores indices of previous node
previous[0] = -1; // all other values are 0
int[] minWeight = new int[Nodes.Count]; // stores minimum weight of the edge of the given node
Fill(minWeight, int.MaxValue); // store max value of int type
minWeight[0] = 0; // first value is set to 0
bool[] isInMST = new bool[Nodes.Count]; // indicates whether a given node is already in the MST
Fill(isInMST, false); // all values are set to false
for (int i = 0; i < Nodes.Count - 1; i++)
{
int minWeightIndex = GetMinimumWeightIndex(minWeight, isInMST); // identifies the minimum weight vale of nodes not in MST
isInMST[minWeightIndex] = true;
for (int j = 0; j < Nodes.Count; j++)
{
Edge <T> edge = this[minWeightIndex, j]; // get edge that connects node with index
int weight = edge != null ? edge.Weight : -1;
if (edge != null && !isInMST[j] && weight < minWeight[j]) // is it in the MST??
{
previous[j] = minWeightIndex; // values are updated
minWeight[j] = weight;
Console.WriteLine(" --> " + edge.ToString());
}
}
}
List <Edge <T> > result = new List <Edge <T> >(); // create list and add to result list
for (int i = 1; i < Nodes.Count; i++)
{
Edge <T> edge = this[previous[i], i];
result.Add(edge);
}
return(result);
}
