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。

import java.util.LinkedList;
import java.util.Queue;

public class Solution {
    
    Queue<TreeNode> queue = new LinkedList<TreeNode>();
    public TreeNode Convert(TreeNode pRootOfTree) {
        
        if(pRootOfTree == null) {
            
            return null;
        }
        inOrder(pRootOfTree);
        TreeNode root = queue.poll();
        root.left = null;
        TreeNode pre = root;
        while(!queue.isEmpty()) {
            
            TreeNode temp = queue.poll();
            pre.right = temp;
            temp.left = pre;
            pre = temp;
        }
        return root;
    }
    private void inOrder(TreeNode node) {
        
        if(node != null) {
            
            inOrder(node.left);
            queue.add(node);
            inOrder(node.right);
        }
    }
}