public static Graph buildTree()
{
Node n = new Node(0);
Graph graph = new Graph(n);
graph.root = n;
graph.root.key = 0;
Node n1 = new Node(1);
Node n2 = new Node(2);
Node n3 = new Node(3);
Node n4 = new Node(4);
Node n5 = new Node(5);
Node n6 = new Node(6);
Node n7 = new Node(7);
Node n8 = new Node(8);
graph.AddEdge(n, n1, 4);
graph.AddEdge(n, n7, 8);
graph.AddEdge(n1, n, 4);
graph.AddEdge(n1, n7, 11);
graph.AddEdge(n1, n2, 8);
graph.AddEdge(n2, n1, 8);
graph.AddEdge(n2, n8, 2);
graph.AddEdge(n2, n3, 7);
graph.AddEdge(n2, n5, 4);
graph.AddEdge(n3, n2, 7);
graph.AddEdge(n3, n5, 14);
graph.AddEdge(n3, n4, 9);
graph.AddEdge(n7, n, 8);
graph.AddEdge(n7, n1, 11);
graph.AddEdge(n7, n8, 7);
graph.AddEdge(n7, n6, 1);
graph.AddEdge(n4, n3, 9);
graph.AddEdge(n4, n5, 10);
graph.AddEdge(n5, n2, 4);
graph.AddEdge(n5, n6, 2);
graph.AddEdge(n5, n3, 14);
graph.AddEdge(n5, n4, 10);
graph.AddEdge(n6, n7, 1);
graph.AddEdge(n6, n8, 6);
graph.AddEdge(n6, n5, 2);
graph.AddEdge(n8, n7, 7);
graph.AddEdge(n8, n2, 2);
graph.AddEdge(n8, n6, 6);
return graph;
}
public Graph(Node root)
{
this.root = root;
if (root != null)
root.key = 0;
}
public void AddNeighbor(Node n, int cost)
{
if (!edgesTo.ContainsKey(n))
edgesTo.Add(n, cost);
}
private void siftDown(List<Node> nodes, int start, int end)
{
int root = start;
while ((root * 2 + 1) <= end)
{
int swap = root;
int child = (2*root+1);
if (nodes[swap].key > nodes[child].key)
swap = child;
if ((child + 1) <= end && nodes[swap].key > nodes[child + 1].key)
swap = child + 1;
if (root != swap)
{
Node n = nodes[root];
nodes[root] = nodes[swap];
nodes[swap] = n;
root = swap;
}
else
return;
}
}
public Graph Prims()
{
Graph mst = new Graph(null);
List<Node> temp = new List<Node>();
Node cur;
heapify(nodeset);
while (nodeset.Count > 0)
{
cur = nodeset[0]; //extract min
nodeset.RemoveAt(0);
temp.Add(cur);
Node n = new Node(cur.data);
if (cur.parent != null)
{
mst.AddEdge(cur.parent, n, cur.key);
cur.parent = null;
}
else
{
mst.nodeset.Add(n);
mst.root = n;
}
foreach (KeyValuePair<Node, int> kv in cur.edgesTo)
{
if (kv.Key.key > kv.Value)
{
kv.Key.key = kv.Value;
kv.Key.parent = n;
}
}
heapify(nodeset);
//siftDown(nodeset, 0, nodeset.Count - 1);
}
this.nodeset = temp;
return mst;
}
public void AddEdge(Node n1, Node n2, int cost)
{
n1.AddNeighbor(n2, cost);
n2.AddNeighbor(n1, cost);
if (!nodeset.Contains(n1))
nodeset.Add(n1);
if (!nodeset.Contains(n2))
nodeset.Add(n2);
}