Deleting an object in a graph

Question

Hi everyone.
I wanted to ask a question about how exactly one deletes an object on a graph.If we say that the graph is like a tree i.e with root , leaves and other nodes that are in between how one deletes a specified object?

Answer 1

A very simple way of describing such a tree/graph structure relatively efficiently is "keep a pointer to your parent/ancestor/predecessor and each parent/ancestor/predecessor has some kind of Collection of all its children/successors. If you want to delete an item (including all its successors) just go to the parent's Collection and remove it.
//this is not very elegant code for maximum simplicity
public class Node {
  public Collection children = new HashSet();
  public Node parent = null;
  public void addChild(Node node){
    node.parent = this;
    this.children.add(node);
  public void remove(){
    this.parent = null;
    parent.children.remove(this);
  public static void main(String[] args){
    Node root = new Node();
    root.addChild(new Node());
    root.addChild(new Node());
    Node n1,n2;
    root.addChild(n1 = new Node());
    n1.addChild(n2 = new Node());
    n2.remove();
    n1.remove();