public static double matchup(int d1, int d2)
 {
     DieStack ds1 = new DieStack(d1);
     DieStack ds2 = new DieStack(d2);
     long numTrials = 0;
     long ds1Wins = 0;
     do
     {
         do
         {
             numTrials++;
             if (ds1.isBetter(ds2))
             {
                 ds1Wins++;
             }
         }
         while (ds2.next());
     }
     while (ds1.next());
     return (double)ds1Wins / (double)numTrials;
 }
 public bool isBetter(DieStack d)
 {
     //Console.WriteLine(this.sum + " versus " + d.sum);
     return (this.sum > d.sum);
 }