SplayNode TranslateLeftToRight(SplayNode node)
{
//只需要存储g的parent的信息
var top = node.Parent;
var g = node;
var p = g.Left;
var x = p.Left;
var temp = x.Right;
x.Right = p;
p.Left = temp;
temp = p.Right;
p.Right = g;
g.Left = temp;
//自动设置了父节点，只需要设置x的父节点
x.Parent = top;
// //父节点交换
// //自动实现了parent设置的时候设置parent的left和right了
// x.Parent = g.Parent;
// g.Parent = p;
// p.Parent = x;
return(x);
}
/// <summary>
/// 向右转（顺时针），情形1，左儿子的左子树插入节点
/// </summary>
/// <param name="node">旋转中心的父节点</param>
/// <returns>旋转中心</returns>
SplayNode SingleRotateRight(SplayNode node)
{
//存储node.parent的信息
var parent = node.Parent;
//旋转中心是父节点的左节点
var center = node.Left;
//父节点的左节点设为中心的右节点
node.Left = center.Right;
// if (node.Left != null)
// {
// node.Left.Parent = node;
// }
//父节点成为中心的右节点
center.Right = node;
// center.Parent = node.Parent;
// node.Parent = center;
center.Parent = parent;
//旋转中心成为根
return(center);
}
/// <summary>
/// 右左旋转 情形3 右儿子的左子树插入
/// </summary>
/// <param name="node">不平衡的点</param>
/// <returns>平衡后的店</returns>
SplayNode DoubleRotateRight(SplayNode node)
{
//先右旋转
node.Right = SingleRotateRight(node.Right);
//左转
node = SingleRotateLeft(node);
return(node);
}
/// <summary>
/// 左右双旋转,情形2 左儿子的右子树插入
/// </summary>
/// <param name="node">不平衡的点</param>
/// <returns>平衡后的点</returns>
SplayNode DoubleRotateLeft(SplayNode node)
{
//先左旋转，旋转中心是左儿子的右儿子
node.Left = SingleRotateLeft(node.Left);
//然后右旋转
node = SingleRotateRight(node);
return(node);
}
private SplayNode Insert(int value, SplayNode tree)
{
if (tree == null)
{
tree = new SplayNode();
tree.Value = value;
}
else
{
if (value > tree.Value)
{
tree.Right = Insert(value, tree.Right);
tree.Right.Parent = tree;
}
else if (value < tree.Value)
{
tree.Left = Insert(value, tree.Left);
tree.Left.Parent = tree;
}
}
return(tree);
}
public SplayTree()
{
root = null;
}
SplayNode Find(int value, SplayNode tree)
{
//加上父节点后
if (tree == null)
{
return(null);
}
if (value > tree.Value)//往下遍历不改变节点
{
tree = Find(value, tree.Right);
}
else if (value < tree.Value)//往下遍历不改变节点
{
tree = Find(value, tree.Left);
}
else
{
//找到了节点
var parent = tree.Parent;
if (parent != null)
{
var grandFather = parent.Parent;
if (grandFather == null)
{ //父节点就是根
if (tree.Equals(parent.Left))
{ //左
tree = SingleRotateRight(parent);
}
else if (tree.Equals(parent.Right))
{//右
tree = SingleRotateLeft(parent);
}
}
else
{
if (parent.Equals(grandFather.Left))//左
{
if (tree.Equals(parent.Left))
{//左 一字形
tree = TranslateLeftToRight(grandFather);
}
else if (tree.Equals(parent.Right))
{//右 z
tree = DoubleRotateLeft(grandFather);
}
}
else
{ //右
if (tree.Equals(parent.Left))
{ //左 z字形
tree = DoubleRotateRight(grandFather);
}
else if (tree.Equals(parent.Right))
{//右 一字形
tree = TranslateRightToLeft(grandFather);
}
}
}
//往上遍历 改变节点
tree = Find(value, tree);
}
else
{//tree就是根节点
}
}
return(tree);
}
public void Find(int value)
{
root = Find(value, root);
}
public void Insert(int value)
{
root = Insert(value, root);
}
