1 package com.algorithm;
2
3 public class BstALL {
4 //输入一棵二叉搜索树，将该二叉搜索树转换成一个排序的双向链表。
5 //要求不能创建任何新的结点，只能调整树中结点指针的指向
6 public TreeNode Convert(TreeNode pRootOfTree) {
7 if(pRootOfTree == null)
8 return null;
9 if(pRootOfTree.left == null && pRootOfTree.right == null)
10 return pRootOfTree;
11 //1、将左子树 构造成双链表，并返回链表头结点
12 TreeNode left = Convert(pRootOfTree.left);
13 TreeNode p = left;
14 //2、定位至左子树双链表最后一个节点
15 while(p!=null && p.right != null){
16 p = p.right;
17 }
18 //3、如果左子树链表不为空，将当前root追加到左子树链表
19 if(left != null){
20 p.right = pRootOfTree;
21 pRootOfTree.left = p;
22 }
23 //4、将右子树构成双链表，并返回链表头结点
24 TreeNode right = Convert(pRootOfTree.right);
25 //如果右子树链表不为空的话，将该链表追加到root节点之后
26 if(right != null){
27 right.left = pRootOfTree;
28 pRootOfTree.right = right;
29 }
30 return left!=null?left:pRootOfTree;
31 }
32 public static void main(String[] args) {
33 TreeNode root = new TreeNode(10);
34 TreeNode rootleft = new TreeNode(6);
35 TreeNode rootright = new TreeNode(14);
36 root.left = rootleft;
37 root.right = rootright;
38
39 TreeNode root2 = new TreeNode(4);
40 TreeNode root3 = new TreeNode(8);
41
42 rootleft.left = root2;
43 rootleft.right = root3;
44
45 TreeNode root4 = new TreeNode(12);
46 TreeNode root5 = new TreeNode(16);
47
48 rootright.left = root4;
49 rootright.right = root5;
50
51 new BstALL().Convert(root);
52
53 }
54 }
