Collezioni - Hashset

using System;
using System.Collections.Generic;

namespace Hash_Dictionary
{
  class Cliente : IEquatable<Cliente>, IComparable<Cliente>
  {
    public string Cognome { get; set; }
    public int Eta { get; set; }
    public Cliente(string cognome, int eta) { Cognome = cognome; Eta = eta; }

    public override int GetHashCode()
    {
      return Cognome.GetHashCode();
    }

    public bool Equals(Cliente other)
    {
      return Cognome.Equals(other.Cognome);
    }

    public int CompareTo(Cliente other)
    {
      return string.Compare(this.Cognome, other.Cognome);
    }
  }

    class Program
    {
    static void Main(string[] args)
    {
      HashSet<string>insieme = new HashSet<string>();

      insieme.Add("Giallo");
      insieme.Add("Rosso");
      //if (!insieme.Add("Giallo")) Console.WriteLine("Rifiutato");
      //Console.WriteLine(insieme.Count);

      //foreach (string s in insieme) Console.WriteLine(s);

      HashSet<Cliente> clientiFilialeA = new HashSet<Cliente>();
      clientiFilialeA.Add(new Cliente("Rossi", 34));
      clientiFilialeA.Add(new Cliente("Verdi", 65));
      clientiFilialeA.Add(new Cliente("Rosa", 65));

      if (!clientiFilialeA.Add(new Cliente("Rossi", 34))) Console.WriteLine("Cliente già presente");


      HashSet<Cliente> clientiFilialeB = new HashSet<Cliente>();
      clientiFilialeB.Add(new Cliente("Rossi", 34));
      clientiFilialeB.Add(new Cliente("Verdi", 65));
      clientiFilialeB.Add(new Cliente("Gialli", 65));

      //clientiFilialeB.IntersectWith(clientiFilialeA);
      //clientiFilialeB.ExceptWith(clientiFilialeA);
      //clientiFilialeB.UnionWith(clientiFilialeA);

      foreach (Cliente c in clientiFilialeB) Console.WriteLine(c.Cognome);

      SortedSet<Cliente> clientiOrdinati = new SortedSet<Cliente>();
      clientiOrdinati.Add(new Cliente("Rossi", 34));
      clientiOrdinati.Add(new Cliente("Verdi", 65));
      clientiOrdinati.Add(new Cliente("Gialli", 65));
      foreach (Cliente c in clientiOrdinati) Console.WriteLine(c.Cognome);
    }
  }
}