//前序线索化二叉树
public void PreThreading(ThrTreeNode <T> root)
{
if (root == null)
{
return;
}
//左指针为空,将左指针指向前驱节点
if (root.lChild == null)
{
root.lChild = pre;
root.Ltag = true;
}
//前一个节点的后继节点指向当前节点
if (pre != null && pre.rChild == null)
{
pre.rChild = root;
pre.Rtag = true;
}
pre = root;
//如果左指针不是索引，处理左子树
if (!root.Ltag)
{
PreThreading(root.lChild);
}
//如果右指针不是索引，处理右子树
if (!root.Rtag)
{
PreThreading(root.rChild);
}
}
//中序遍历线索二叉树，按照后继方式进行遍历
public void InOrderTraversal(ThrTreeNode <T> root)
{
//1、找中序遍历方式最开始的节点
while (root != null && !root.Ltag)
{
root = root.lChild;
}
while (root != null)
{
//Console.Write(root.Data + " ");
if (!root.Data.Equals('#'))
{
resultthrin += root.Data;
}
//如果右指针是线索
if (root.Rtag)
{
root = root.rChild;
}
//如果右指针不是线索，找到右子树开始的节点(即右子树最左边的结点)
else
{
root = root.rChild;
while (root != null && !root.Ltag)
{
root = root.lChild;
}
}
}
}
//中序遍历线索化
// 如果当前结点无左孩子，则刚刚访问的pre结点为当前结点的前驱
// 如果刚刚访问的pre结点无右孩子，则当前结点为pre结点的后继
public void InTreading(ThrTreeNode <T> root)
{
if (root == null)
{
return;
}
//处理左子树
InTreading(root.lChild);
//左指针为空,将左指针指向前驱节点
if (root.lChild == null)
{
root.lChild = pre;
root.Ltag = true;
}
//前一个节点的后继节点指向当前节点
if (pre != null && pre.rChild == null)
{
pre.rChild = root;
pre.Rtag = true;
}
pre = root;
//处理右子树
InTreading(root.rChild);
}
private void button1_Click(object sender, EventArgs e)
{
char[] data = (textBox1.Text.Trim()).ToCharArray();
//char[] data = { 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J' };
BinaryTree <char> tree = new BinaryTree <char>(data);
tree.leaves = 0;
tree.PreTraversal(tree.Head);
tree.InTraversal(tree.Head);
tree.LastTraversal(tree.Head);
ThrBinaryTree <char> tree1 = new ThrBinaryTree <char>();
ThrTreeNode <char> root = tree1.CreatBinaryTree(data, 0);
//Console.WriteLine("二叉树中序线索化...");
tree1.InTreading(root);
//Console.Write("中序按后继节点遍历线索二叉树结果：");
tree1.InOrderTraversal(root);
//Console.WriteLine();
//Console.Write("中序按前驱节点遍历线索二叉树结果：");
//Console.WriteLine();
ThrTreeNode <char> root2 = tree1.CreatBinaryTree(data, 0);
//Console.WriteLine("二叉树先序线索化...");
tree1.PreThreading(root2);
//Console.Write("先序按后继节点遍历线索二叉树结果：");
tree1.PreInTraversal(root2);
textBox2.Text = tree.resultpre;
textBox3.Text = tree.resultin;
textBox4.Text = tree.resultpost;
}
//通过数组构建二叉树
public ThrTreeNode <T> CreatBinaryTree(T[] vals, int index)
{
ThrTreeNode <T> root = null;
if (index < vals.Length)
{
root = new ThrTreeNode <T>(vals[index]);
root.lChild = CreatBinaryTree(vals, index * 2 + 1);
root.rChild = CreatBinaryTree(vals, index * 2 + 2);
}
return(root);
}
//前序遍历线索二叉树（按照后继线索遍历）
public void PreInTraversal(ThrTreeNode <T> root)
{
while (root != null)
{
while (!root.Ltag)
{
//Console.Write(root.Data + " ");
if (!root.Data.Equals('#'))
{
resultthrpre += root.Data;
}
root = root.lChild;
}
//Console.Write(root.Data + " ");
if (!root.Data.Equals('#'))
{
resultthrpre += root.Data;
}
root = root.rChild;
}
}
public ThrTreeNode(T val)
{
this.data = val;
this.lChild = null;
this.rChild = null;
}