public void Split(int x, out Treap L, out Treap R)
{
Treap newTree = null;
if (this.x <= x)
{
if (Right == null)
{
R = null;
}
else
{
Right.Split(x, out newTree, out R);
}
L = new Treap(this.x, y, Left, newTree);
}
else
{
if (Left == null)
{
L = null;
}
else
{
Left.Split(x, out L, out newTree);
}
R = new Treap(this.x, y, newTree, Right);
}
}
private Treap(int x, int y, Treap left = null, Treap right = null, Treap parent = null)
{
this.x = x;
this.y = y;
Left = left;
Right = right;
Parent = parent;
}
public Treap Add(int x)
{
Treap l, r;
Split(x, out l, out r);
Treap m = new Treap(x, rand.Next());
return(Merge(Merge(l, m), r));
}
public static Treap Merge(Treap L, Treap R)
{
if (L == null)
{
return(R);
}
if (R == null)
{
return(L);
}
if (L.y > R.y)
{
var newR = Merge(L.Right, R);
return(new Treap(L.x, L.y, L.Left, newR));
}
else
{
var newL = Merge(L, R.Left);
return(new Treap(R.x, R.y, newL, R.Right));
}
}
public static Treap Build(int[] xs, int[] ys)
{
var tree = new Treap(xs[0], ys[0]);
var last = tree;
for (int i = 1; i < xs.Length; ++i)
{
if (last.y > ys[i])
{
last.Right = new Treap(xs[i], ys[i], parent: last);
last = last.Right;
}
else
{
Treap cur = last;
while (cur.Parent != null && cur.y <= ys[i])
{
cur = cur.Parent;
}
if (cur.y <= ys[i])
{
last = new Treap(xs[i], ys[i], cur);
}
else
{
last = new Treap(xs[i], ys[i], cur.Right, null, cur);
cur.Right = last;
}
}
}
while (last.Parent != null)
{
last = last.Parent;
}
return(last);
}