public DistanceElement getElement(long id) {
		
		if (!vector.containsKey(id))
			vector.put(id, new DistanceElement(id));
		
		return vector.get(id);
	}
public DistanceElement getElement ( long id ) { if ( ! vector . containsKey ( id ) ) vector . put ( id , new DistanceElement ( id ) ) ; return vector . get ( id ) ; }
Gets an element of the distance vector, based on the given node id. If a DistanceElement object with the given id does
not exist in the vector, a new object with the id is added to it. Then, the element with the given id as key is returned
in the end.

@param id the id whose associated DistanceElement object is to be returned
@return the value to which the specified id is mapped