Dictionary with two keys?

Question

I am keeping track of values in a console. Two people "duel" against each other and I was using a dictionary to keep the names recorded along with damage done.

var duels = new Dictionary<string, string>();
duels.Add("User1", "50");
duels.Add("User2","34");

I'm trying to store both users in the same dictionary row, so it could be verified as User1 is dueling against User2. This way if another duel started, it would not interfere with User1 or User2.

duels.Add("KeyUser1","KeyUser2","50","34",.../*Other attributes of the duel*/);

I need two keys so I can check where the user's damage will go. The damage will always go to the other key--vice versa. What can I do to make this work?

Thank you.

Answer 1

public class Duel
{
  public string User1 {get; protected set;}
  public string User2 {get; protected set;}
  public Duel(string user1, string user2)
  {
    User1 = user1;
    User2 = user2;
  }

  public HashSet<string> GetUserSet()
  {
    HashSet<string> result = new HashSet<string>();
    result.Add(this.User1);
    result.Add(this.User2);
    return result;
  }

  //TODO ... more impl
}

Let's make some duels. CreateSetComparer allows the dictionary to use the values of the set for equality testing.

List<Duel> duelSource = GetDuels();
Dictionary<HashSet<string>, Duel> duels =
  new Dictionary<HashSet<string>, Duel>(HashSet<string>.CreateSetComparer());

foreach(Duel d in duelSource)
{
  duels.Add(d.GetUserSet(), d);
}

And finding a duel:

HashSet<string> key = new HashSet<string>();
key.Add("User1");
key.Add("User2");
Duel myDuel = duels[key];

Answer 2

You could try making a custom data type for the key:

class DualKey<T> : IEquatable<DualKey<T>> where T : IEquatable<T>
{
    public T Key0 { get; set; }
    public T Key1 { get; set; }

    public DualKey(T key0, T key1)
    {
        Key0 = key0;
        Key1 = key1;
    }

    public override int GetHashCode()
    {
        return Key0.GetHashCode() ^ Key1.GetHashCode();
    }

    public bool Equals(DualKey<T> obj)
    {
        return (this.Key0.Equals(obj.Key0) && this.Key1.Equals(obj.Key1))
            || (this.Key0.Equals(obj.Key1) && this.Key0.Equals(obj.Key0));
    }
}

Then use a Dictionary<DualKey<string>, string>;