//Delete incoming edges
private void DeleteFromEdgeList(string s)
{
for (VertexNode p = start; p != null; p = p.nextVertex)
{
if (p.firstEdge == null)
{
continue;
}
if (p.firstEdge.endVertex.name.Equals(s))
{
p.firstEdge = p.firstEdge.nextEdge;
e--;
}
else
{
EdgeNode q = p.firstEdge;
while (q.nextEdge != null)
{
if (q.nextEdge.endVertex.name.Equals(s))
{
q.nextEdge = q.nextEdge.nextEdge;
e--;
break;
}
q = q.nextEdge;
}
}
}
}
public void InsertVertex(string s)
{
VertexNode temp = new VertexNode(s);
if (start == null)
{
start = temp;
}
else
{
VertexNode p = start;
while (p.nextVertex != null)
{
if (p.name.Equals(s))
{
Console.WriteLine("Vertex exists");
return;
}
p = p.nextVertex;
}
if (p.name.Equals(s))
{
Console.WriteLine("Vertex exists");
return;
}
p.nextVertex = temp;
}
n++;
}
public VertexNode FindVertex(string s)
{
VertexNode p = start;
while (p != null)
{
if (p.name.Equals(s))
{
return(p);
}
p = p.nextVertex;
}
return(null);
}
public void InsertEdge(string s1, string s2)
{
if (s1.Equals(s2))
{
Console.WriteLine("Invalid Edge: Start and End vertices are same");
return;
}
VertexNode u = FindVertex(s1);
VertexNode v = FindVertex(s2);
if (u == null)
{
Console.WriteLine("Vertex does not exist");
return;
}
if (v == null)
{
Console.WriteLine("Vertex does not exist");
return;
}
EdgeNode temp = new EdgeNode(v);
if (u.firstEdge == null)
{
u.firstEdge = temp;
e++;
}
else
{
EdgeNode p = u.firstEdge;
while (p.nextEdge != null)
{
if (p.nextEdge.endVertex.Equals(v))
{
Console.WriteLine("Edge is present");
return;
}
}
p.nextEdge = temp;
e++;
}
}
private void DeleteFromVertexList(string s)
{
if (start == null)
{
Console.WriteLine("No Vertices to be deleted");
return;
}
if (start.name.Equals(s))
{
for (EdgeNode q = start.firstEdge; q != null; q = q.nextEdge)
{
e--;
}
start = start.nextVertex;
n--;
}
else
{
VertexNode p = start;
while (p.nextVertex != null)
{
if (p.nextVertex.name.Equals(s))
{
break;
}
p = p.nextVertex;
}
if (p.nextVertex == null)
{
Console.WriteLine("Vertex not found");
return;
}
else
{
for (EdgeNode q = p.nextVertex.firstEdge; q != null; q = q.nextEdge)
{
e--;
}
p.nextVertex = p.nextVertex.nextVertex;
n--;
}
}
}
public EdgeNode(VertexNode v)
{
endVertex = v;
}
