/// <summary>
/// 左树平衡处理
/// </summary>
/// <param name="node"></param>
private AvlTreeNote <TKey> LeftBalance(AvlTreeNote <TKey> node)
{
if (_isBalance)
{
return(node);
}
var leftNode = node.LChild;
switch (leftNode.Height)
{
case 1:
node.Height = leftNode.Height = 0;
node = R_Rotate(node);
break;
case -1:
node.Height = leftNode.Height = 0;
node.LChild = L_Rotate(leftNode);
node = R_Rotate(node);
break;
}
return(node);
}
private AvlTreeNote <TKey> RightBalance(AvlTreeNote <TKey> node)
{
if (_isBalance)
{
return(node);
}
var rightNode = node.RChild;
switch (rightNode.Height)
{
case -1:
node.Height = rightNode.Height = 0;
node = L_Rotate(node);
break;
case 1:
node.Height = rightNode.Height = 0;
node.RChild = R_Rotate(rightNode);
node = L_Rotate(node);
break;
}
return(node);
}
/// <summary>
/// 左旋操作
/// </summary>
/// <param name="node"></param>
private AvlTreeNote <TKey> L_Rotate(AvlTreeNote <TKey> node)
{
var temp = node.RChild;
node.RChild = temp.LChild;
temp.LChild = node;
_isBalance = true;
return(temp);
}
/// <summary>
/// 查找二叉树
/// </summary>
/// <param name="key"></param>
/// <param name="node"></param>
/// <returns></returns>
public AvlTreeNote <TKey> Find(TKey key, AvlTreeNote <TKey> node)
{
if (node == null)
{
return(null);
}
if (key.CompareTo(node.Key) < 0)
{
node = Find(key, node.LChild);
}
else if (key.CompareTo(node.Key) > 0)
{
node = Find(key, node.RChild);
}
return(node);
}
/// <summary>
/// 用于删除该节点移动节点
/// </summary>
/// <param name="node"></param>
/// <param name="findNode"></param>
/// <returns></returns>
private AvlTreeNote <TKey> Move(AvlTreeNote <TKey> node, AvlTreeNote <TKey> findNode)
{
AvlTreeNote <TKey> moveNode;
if (findNode != null)
{
if (findNode.RChild != null)
{
moveNode = findNode.RChild;
findNode.RChild = null;
}
else
{
findNode.LChild = null;
moveNode = findNode;
}
if (node.LChild != moveNode)
{
moveNode.LChild = node.LChild;
}
if (node.RChild != moveNode)
{
moveNode.RChild = node.RChild;
}
}
else
{
moveNode = null;
}
node.LChild = null;
node.RChild = null;
node.Key = default(TKey);
node.Height = 0;
return(moveNode);
}
private AvlTreeNote <TKey> Remove(TKey key, AvlTreeNote <TKey> node)
{
if (node == null)
{
return(null);
}
if (key.CompareTo(node.Key) < 0)
{
if (node.LChild == null)
{
return(node);
}
node.LChild = Remove(key, node.LChild);
switch (node.Height)
{
case 1:
node.Height = 0;
break;
case 0:
node.Height = -1;
break;
case -1:
// 要进行旋转
node.Height = 0;
return(node.LChild == null?RightBalance(node) : LeftBalance(node));
}
}
else if (key.CompareTo(node.Key) > 0)
{
if (node.RChild == null)
{
return(node);
}
node.RChild = Remove(key, node.RChild);
switch (node.Height)
{
case 1:
// 要进行旋转
node.Height = 0;
return(node.RChild == null?LeftBalance(node) : RightBalance(node));
break;
case 0:
node.Height = 1;
break;
case -1:
node.Height = 0;
break;
}
}
else if (key.CompareTo(node.Key) == 0)
{
var findNode = Remove(key, node.LChild);
node = Move(node, findNode);
}
_isBalance = false;
return(node);
}
/// <summary> /// 删除节点 /// </summary> /// <param name="key"></param> public void Remove(TKey key) => Root = Remove(key, Root);
/// <summary>
/// 插入到指定节点下
/// </summary>
/// <param name="key"></param>
/// <param name="node"></param>
/// <returns></returns>
private AvlTreeNote <TKey> Insert(TKey key, AvlTreeNote <TKey> node)
{
if (node == null)
{
node = new AvlTreeNote <TKey>(key, null, null);
}
else
{
// 如果树里已经存在该节点，直接返回为null
if (key.CompareTo(node.Key) == 0)
{
return(null);
}
if (key.CompareTo(node.Key) < 0)
{
// 应该在左树进行搜索插入
node.LChild = Insert(key, node.LChild);
if (node.LChild == null)
{
return(node);
}
switch (node.Height)
{
case 1:
return(LeftBalance(node));
case 0:
node.Height = _isBalance ? 0 : 1;
break;
case -1:
node.Height = 0;
break;
}
}
else
{
// 应该在右树进行搜索插入
node.RChild = Insert(key, node.RChild);
if (node.RChild == null)
{
return(node);
}
switch (node.Height)
{
case 1:
node.Height = 0;
break;
case 0:
node.Height = _isBalance ? 0 : -1;
break;
case -1:
return(RightBalance(node));
}
}
}
_isBalance = false;
return(node);
}
private bool _isBalance; // 标志是否平衡过二叉树
/// <summary>
/// 插入节点
/// </summary>
/// <param name="key"></param>
/// <returns></returns>
public AvlTreeNote <TKey> Insert(TKey key) => Root = Insert(key, Root);
public AvlTreeNote(TKey key, AvlTreeNote <TKey> lChild, AvlTreeNote <TKey> rChild)
{
Key = key;
LChild = lChild;
RChild = rChild;
}