Java - Which is the best implementation structure for Graph?

Question

The graph is very large but undirected. Edges are unweighted.

In my implementation, I have to find the vertex with max degree and do deletion on both vertexes and edges.

Answer 1

Depends on what other requirements you have. A naive, simple approach could be

class Node
{
  List edges;
  int id;
}

where you'd have a List of all the nodes in the graph. The problem is this can become inconsistent; e.g. node A might be in node B's edges list, but node B might not be in node A's list. To get around this, you could model it as such:

class Edge
{
  Node incidentA;
  Node incidentB;
}

class Node
{
  int id;
}

Again, you'd have List and List of all the edges and nodes in the system. Of course analyzing this data structure would be done in a very different way than in the other approach.