/* Parent Parent
* |- |+
* B A
* -/ \ / \+
* A BL -> AL B
* / \- +/ \
* AL C C BR
*
* - marks connections that are dettached
* + marks connections that are created
*/
private AvlTreeNode <T> _rotateRight(AvlTreeNode <T> b)
{
AvlTreeNode <T> a = b.Left;
AvlTreeNode <T> parent = b.Parent; // may be null if B was root
AvlTreeNode <T> c = a.Right; // may be null
var direction = b.Direction;
Debug.Assert(a != null);
// a.Left remains so no need to change this
// b.Right remains so no need to change this
_dettachFromParent(b); // b from parent
_dettachFromParent(a); // a from b
_dettachFromParent(c); // c from a
_attachToParentEdge(c, b.EdgeLeft());
_attachToParentEdge(b, a.EdgeRight());
_attachToParentEdge(a, parent.EdgeTo(direction));
_recalc(b);
_recalc(a);
return(a);
}
private AvlTreeNode <T> rec_createRangeSubtree(T[] items, int start, int end)
{
if (start > end)
{
return(null);
}
var mid = (start + end) / 2;
var item = items[mid];
var node = new AvlTreeNode <T>(item);
var left = rec_createRangeSubtree(items, start, mid - 1);
var right = rec_createRangeSubtree(items, mid + 1, end);
if (left != null)
{
_attachToParentEdge(left, node.EdgeLeft());
}
if (right != null)
{
_attachToParentEdge(right, node.EdgeRight());
}
_recalc(node);
return(node);
}
