public bool Find(int item)
{
//return Find(item, root);
BSNode temp = root;
while (true)
{
if (temp == null)
{
return(false);
}
if (temp.Data == item)
{
return(true);
}
if (item > temp.Data)
{
temp = temp.RightChild;
}
else
{
temp = temp.LeftChild;
}
}
}
public bool Delete(int item)
{
BSNode temp = root;
while (true)
{
if (temp == null)
{
return(false);
}
if (temp.Data == item)
{
Delete(temp);
return(true);
}
if (item > temp.Data)
{
temp = temp.RightChild;
}
else
{
temp = temp.LeftChild;
}
}
}
private void MiddleTraversal(BSNode node) //中序遍历
{
if (node == null)
{
return;
}
MiddleTraversal(node.LeftChild);
Console.Write(node.Data + " ");
MiddleTraversal(node.RightChild);
}
/// <summary>
/// 中序遍历
/// </summary>
/// <param name="root"></param>
private void InorderTraversal(BSNode root)
{
if (root == null)
{
return;
}
InorderTraversal(root.LeftNode);
Console.Write(root.data + " ");
InorderTraversal(root.RightNode);
}
private BSNode SearchMaxNode(BSNode root)
{
if (root == null)
{
return(null);
}
if (root.RightNode == null)
{
return(root);
}
else
{
return(SearchMaxNode(root.RightNode));
}
}
private BSNode SearchMinNode(BSNode root)
{
if (root == null)
{
return(null);
}
if (root.LeftNode == null)
{
return(root);
}
else
{
return(SearchMinNode(root.LeftNode));
}
}
public void Delete(BSNode node)
{
if (node.LeftChild == null && node.RightChild == null) //该节点是叶子节点时
{
if (node.Parent == null)
{
root = null;
}
else if (node.Parent.LeftChild == node)
{
node.Parent.LeftChild = null;
}
else if (node.Parent.RightChild == node)
{
node.Parent.RightChild = null;
}
return;
}
if (node.LeftChild == null && node.RightChild != null) //该节点只有右孩子时，好像有问题
{
node.Data = node.RightChild.Data;
node.RightChild = null;
return;
}
if (node.LeftChild != null && node.RightChild == null) //该节点只有左孩子时
{
node.Data = node.LeftChild.Data;
node.LeftChild = null;
return;
}
BSNode temp = node.RightChild; //该节点左右孩子都有时，取其右子树上的最小值补在该节点
while (true)
{
if (temp.LeftChild != null)
{
temp = temp.LeftChild;
}
else
{
break;
}
}
node.Data = temp.Data;
Delete(temp);
}
public void Add(int item)
{
BSNode newNode = new BSNode(item);
if (root == null)
{
root = newNode;
root.Parent = null;
nodeCount = 1;
}
else
{
//如果已经存在，则不进行插入
if (SearchNode(root, item) != null)
{
Console.WriteLine(item + " 已存在");
return;
}
BSNode tempNode = null;
BSNode rootNode = root;//这里只是将root的指针传给了rootNode
while (rootNode != null)
{
tempNode = rootNode;
newNode.Parent = tempNode;
//这里只是更改了rootNode的指向，并不影响root
rootNode = rootNode.data > item ? rootNode.LeftNode : rootNode.RightNode;
}
//Console.WriteLine("rootNode：" + (rootNode == null) + "===" + tempNode.data + "~~~" + root.data);
if (item < tempNode.data)
{
tempNode.LeftNode = newNode;
}
else
{
tempNode.RightNode = newNode;
}
nodeCount++;
}
}
public void TreeTraversal(BSNode root = null)
{
if (root != null)
{
BreadthFirstTravel(root);
}
else
{
if (this.root == null)
{
return;
}
else
{
BreadthFirstTravel(this.root);
}
}
}
private bool Find(int item, BSNode node)
{
if (node == null)
{
return(false);
}
if (node.Data == item)
{
return(true);
}
else if (item > node.Data)
{
return(Find(item, node.RightChild));
}
else
{
return(Find(item, node.LeftChild));
}
}
public void Add(int item)
{
BSNode newNode = new BSNode(item);
if (root == null)
{
root = newNode;
}
else
{
BSNode temp = root;
while (true)
{
if (item >= temp.Data) //放在temp的右边
{
if (temp.RightChild == null)
{
temp.RightChild = newNode;
newNode.Parent = temp;
break;
}
else
{
temp = temp.RightChild;
}
}
else //放在temp的左边
{
if (temp.LeftChild == null)
{
temp.LeftChild = newNode;
newNode.Parent = temp;
break;
}
else
{
temp = temp.LeftChild;
}
}
}
}
}
public BSNode SearchNode(BSNode root, int key)
{
if (root == null)
{
return(null);
}
if (key > root.data)
{
return(SearchNode(root.RightNode, key));
}
else if (key < root.data)
{
return(SearchNode(root.LeftNode, key));
}
else
{
return(root);
}
}
private void BreadthFirstTravel(BSNode root)
{
Queue <BSNode> que = new Queue <BSNode>();
que.Enqueue(root);
while (que.Count != 0)
{
root = que.Peek();
Console.Write(root.data + " ");
que.Dequeue();
if (root.LeftNode != null)
{
que.Enqueue(root.LeftNode);
}
if (root.RightNode != null)
{
que.Enqueue(root.RightNode);
}
}
}
private void Delete(BSNode root, int data)
{
//root = null;//没有效果
//this.root = null;//这个才能真正赋值为null
BSNode tempRoot = root;
if (root == null)
{
return;
}
//如果找到了指定节点
if (data == tempRoot.data)
{
//如果node是叶子节点
if (tempRoot.LeftNode == null && tempRoot.RightNode == null)
{
//Console.WriteLine("设置为空......");
//tempRoot = null;//为什么没有效果
// root = null;//为什么没有效果
//为什么这样就可以
if (tempRoot.Parent == null)
{
//tempRoot = null;//没有效果
//root = null;//同样没有效果
this.root = null;
}
else if (tempRoot.Parent.LeftNode != null)
{
tempRoot.Parent.LeftNode = null;
}
else if (tempRoot.Parent.RightNode != null)
{
tempRoot.Parent.RightNode = null;
}
}
else
{
//如果左右节点都不为空
if (tempRoot.LeftNode != null && tempRoot.RightNode != null)
{
//method1：以右子树内的最小节点取代该节点
BSNode minR = tempRoot.RightNode;
if (minR.LeftNode == null)
{
tempRoot.data = minR.data;
tempRoot.RightNode = null;
//minR.data = 70;//进行了改变啊
//minR = null;//直接使用miR = null为什么不行?
}
else
{
BSNode minRParent = null;
while (minR.LeftNode != null)
{
minRParent = minR;
minR = minR.LeftNode;
}
minRParent.LeftNode = null;
tempRoot.data = minR.data;
tempRoot.RightNode = minRParent;
}
//method2：以左子树内的最大节点取代该节点
}
//如果左节点不为空
else if (tempRoot.LeftNode != null && tempRoot.RightNode == null)
{
tempRoot = tempRoot.LeftNode;
}
//如果右节点不为空
else if (tempRoot.LeftNode == null && tempRoot.RightNode != null)
{
tempRoot = tempRoot.RightNode;
}
}
}
else if (data > tempRoot.data)
{
Delete(tempRoot.RightNode, data);
}
else if (data < tempRoot.data)
{
Delete(tempRoot.LeftNode, data);
}
}