private STreeNode <T> SingleRotateLeft(STreeNode <T> x)
{
var p = x.Parent;
p.LeftChild = x.RightChild;
if (x.RightChild != null)
{
x.RightChild.Parent = p;
}
x.RightChild = p;
x.Parent = p.Parent;
p.Parent = x;
//if (x.Parent != null)
//{
// if (x.Key.CompareTo(x.Parent.Key) < 0)
// {
// x.Parent.LeftChild = x;
// }
// else
// {
// x.Parent.RightChild = x;
// }
//}
return(x);
}
private STreeNode <T> SingleRotateRight(STreeNode <T> x)
{
var p = x.Parent;
p.RightChild = x.LeftChild;
// 此行务必要有
if (x.LeftChild != null)
{
x.LeftChild.Parent = p;
}
x.LeftChild = p;
x.Parent = p.Parent;
p.Parent = x;
// 以下代码我觉得应该有，但是不加好像也没有关系
// 作用是让旋转之后的x的parent指向它，而非原来的child
// 不过因为x会停的旋转直到成为root
// 所以parent没有指向它的bug会在后续的旋转中被自动修正，Σ(っ °Д °;)っ
//if (x.Parent != null)
//{
// if (x.Key.CompareTo(x.Parent.Key) < 0)
// {
// x.Parent.LeftChild = x;
// }
// else
// {
// x.Parent.RightChild = x;
// }
//}
return(x);
}
private STreeNode <T> ZigzigRight(STreeNode <T> x)
{
var p = x.Parent;
var g = p.Parent;
p = SingleRotateRight(p);
return(SingleRotateRight(x));
}
private void RotateToRoot(STreeNode <T> node)
{
while (node.Parent != null)
{
node = Rotate(node);
}
Root = node;
}
private STreeNode <T> ZigzagLeft(STreeNode <T> x)
{
var p = x.Parent;
var g = p.Parent;
x = SingleRotateRight(x);
return(SingleRotateLeft(x));
}
private STreeNode <T> FindMax(STreeNode <T> root)
{
while (root.RightChild != null)
{
root = root.LeftChild;
}
RotateToRoot(root);
return(root);
}
public void Delete(T key)
{
var p = Find(key);
var tl = p.LeftChild;
var tr = p.RightChild;
var newRoot = FindMax(tl);
newRoot.RightChild = tr;
if (tr != null)
{
tr.Parent = newRoot;
}
Root = newRoot;
}
/// <summary>
/// 插入已存在的key，不做任何改变
/// </summary>
/// <param name="root"></param>
/// <param name="key"></param>
/// <param name="parent"></param>
/// <returns></returns>
private STreeNode <T> Insert(STreeNode <T> root, T key, STreeNode <T> parent)
{
if (root == null)
{
return(new STreeNode <T>(key, parent));
}
if (root.Key.CompareTo(key) > 0)
{
root.LeftChild = Insert(root.LeftChild, key, root);
}
else if (root.Key.CompareTo(key) < 0)
{
root.RightChild = Insert(root.RightChild, key, root);
}
return(root);
}
public STreeNode <T> Rotate(STreeNode <T> x)
{
if (x.Parent == null)
{
return(x);
}
// x只有Parent，没有Grandparent
if (x.Parent.Parent == null)
{
if (x.Key.CompareTo(x.Parent.Key) < 0)
{
return(SingleRotateLeft(x));
}
else
{
return(SingleRotateRight(x));
}
}
// x有Grandparent
if (x.Key.CompareTo(x.Parent.Parent.Key) < 0)
{
if (x.Key.CompareTo(x.Parent.Key) < 0)
{
return(ZigzigLeft(x));
}
else
{
return(ZigzagLeft(x));
}
}
else
{
if (x.Key.CompareTo(x.Parent.Key) < 0)
{
return(ZigzagRight(x));
}
else
{
return(ZigzigRight(x));
}
}
}
private STreeNode <T> Find(STreeNode <T> root, T key)
{
if (root == null)
{
return(null);
}
if (root.Key.CompareTo(key) > 0)
{
return(Find(root.LeftChild, key));
}
else if (root.Key.CompareTo(key) < 0)
{
return(Find(root.RightChild, key));
}
else
{
RotateToRoot(root);
return(root);
}
}
public STreeNode(T key, STreeNode <T> parent)
{
Key = key;
Parent = parent;
}
public void Insert(T key)
{
Root = Insert(Root, key, null);
}
