# 36. 二叉搜索树与双向链表

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## 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。

<div align="center"> <img src="pics/05a08f2e-9914-4a77-92ef-aebeaecf4f66.jpg" width="400"/> </div><br>

## 解题思路

```java
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);
}
```






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