private HeapNode MergeNodes(HeapNode l, HeapNode r)
{
if (l == null)
{
return(r);
}
if (r == null)
{
return(l);
}
if (l.Value.CompareTo(r.Value) > 0)
{
r.AddFirstChild(l);
return(r);
}
else
{
l.AddLastChild(r);
return(l);
}
}