- 题目描述

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。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。

- 解题思路

递归

- Java实现

/**public class TreeNode {    int val = 0;    TreeNode left = null;    TreeNode right = null;     public TreeNode(int val) {        this.val = val;     } }*/public class Solution {    private TreeNode pre = null;    private TreeNode head = null;         public TreeNode Convert(TreeNode root) {        inOrder(root);        return head;    }         private void inOrder(TreeNode node) {        if (node == null)            return;        inOrder(node.left);        node.left = pre;        if (pre != null)            pre.right = node;        pre = node;        if (head == null)            head = node;        inOrder(node.right);  }}