public static TreapNode Merge(TreapNode a, TreapNode b)
{
if (a == null || b == null)
{
return(a ?? b);
}
if (rand.NextDouble() < (double)GetSize(a) / (GetSize(a) + GetSize(b)))
{
a.PutDown();
if (a.r != null)
{
a.r.parent = null;
}
a.r = Merge(a.r, b);
a.r.parent = a;
a.Maintain();
return(a);
}
else
{
b.PutDown();
if (b.l != null)
{
b.l.parent = null;
}
b.l = Merge(a, b.l);
b.l.parent = b;
b.Maintain();
return(b);
}
}
public static void Split(TreapNode o, out TreapNode a, out TreapNode b, int position)
{
if (position < 0)
{
MyLogger.Log($"TreapNode: position = {position}");
position = 0;
}
if (position > GetSize(o))
{
MyLogger.Log($"TreapNode: position = {position}");
position = GetSize(o);
}
//MyLogger.Assert(0 <= position && position <= GetSize(o));
if (o == null)
{
a = b = null; return;
}
o.PutDown();
if (position <= GetSize(o.l))
{
b = o;
if (b.l != null)
{
b.l.parent = null;
}
Split(b.l, out a, out b.l, position);
if (b.l != null)
{
b.l.parent = b;
}
b.Maintain();
}
else
{
a = o;
if (a.r != null)
{
a.r.parent = null;
}
Split(a.r, out a.r, out b, position - GetSize(a.l) - 1);
if (a.r != null)
{
a.r.parent = a;
}
a.Maintain();
}
}