static private string Choose(WDict w)
{
long total = w.Sum(t => t.Value);
while (true)
{
int i = r.Next(0, w.Count);
double c = r.NextDouble();
System.Collections.Generic.KeyValuePair <string, uint> k = w.ElementAt(i);
if (c < (double)k.Value / total)
{
return(k.Key);
}
}
}
