二叉搜索树

public class BinarSearchTree
{
private Node _tree;

public BinarSearchTree(List datas)
{
if (datas != null)
{
foreach (var item in datas)
{
Insert(item);
}
}
}

///

/// 插入
///

///
public void Insert(int data)
{
if (_tree == null)
{
_tree = new Node(data);
}
else
{
var current = _tree;

while (current != null)
{
if (data > current.Data)
{
if (current.Right == null)
{
current.Right = new Node(data, current);
break;
}

current = current.Right;
}
else if (data < current.Data)
{
if (current.Left == null)
{
current.Left = new Node(data, current);
break;
}

current = current.Left;
}
}
}
}

///

/// 删除
///

///
public void Delete(int data)
{
var node = Find(data);
if (node == null) return;

if (node.Left == null && node.Right == null)
{
if (node.Parent == null)
{
_tree = null;
}
else
{
// 直接删除即可
DeleteFromParent(node);
}
}
else if (node.Left != null && node.Right != null)
{
if (node.Parent == null)
{
_tree = null;
}
else
{
// 查找右子树最大节点
var minNode = node.Right;
var currentNode = node.Right;
while (currentNode != null)
{
minNode = currentNode;
currentNode = minNode.Left;
}

DeleteFromParent(minNode);
ReplaceChildNode(node, minNode);
}
}
else
{
// 有一个子节点，则直接将子节点挂到父节点下
var child = node.Left ?? node.Right;

if (node.Parent == null)
{
_tree = child;
}
else
{
ReplaceChildNode(node, child);
}
}
}

private void ReplaceChildNode(Node node, Node newNode)
{
newNode.Parent = node.Parent;

if (node.Parent.Left == node)
{
node.Parent.Left = newNode;
}

if (node.Parent.Right == node)
{
node.Parent.Right = newNode;
}
}

private void DeleteFromParent(Node node)
{
if (node.Parent.Left == node)
{
node.Parent.Left = null;
}

if (node.Parent.Right == node)
{
node.Parent.Right = null;
}
}

///

/// 查找
///

///
///
public Node Find(int data)
{
var current = _tree;

while (current != null)
{
if (data > current.Data)
{
current = current.Right;
}
else if (data < current.Data)
{
current = current.Left;
}
else
{
return current;
}
}

return null;
}
}

public class Node
{
public Node(int data, Node parent = null)
{
this.Data = data;
Parent = parent;
}

public int Data { get; set; }
public Node Left { get; set; }
public Node Right { get; set; }
public Node Parent { get; set; }
}