<p>Given the <code>head</code> of a singly linked list where elements are sorted in <strong>ascending order</strong>, convert <em>it to a </em><span data-keyword="height-balanced"><strong><em>height-balanced</em></strong></span> <em>binary search tree</em>.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2020/08/17/linked.jpg" style="width: 500px; height: 388px;" />
<pre>
<strong>Input:</strong> head = [-10,-3,0,5,9]
<strong>Output:</strong> [0,-3,9,-10,null,5]
<strong>Explanation:</strong> One possible answer is [0,-3,9,-10,null,5], which represents the shown height balanced BST.
</pre>

<p><strong class="example">Example 2:</strong></p>

<pre>
<strong>Input:</strong> head = []
<strong>Output:</strong> []
</pre>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li>The number of nodes in <code>head</code> is in the range <code>[0, 2 * 10<sup>4</sup>]</code>.</li>
	<li><code>-10<sup>5</sup> &lt;= Node.val &lt;= 10<sup>5</sup></code></li>
</ul>

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode() : val(0), next(nullptr) {}
 *     ListNode(int x) : val(x), next(nullptr) {}
 *     ListNode(int x, ListNode *next) : val(x), next(next) {}
 * };
 */
/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode() : val(0), left(nullptr), right(nullptr) {}
 *     TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
 *     TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
 * };
 */
class Solution {
public:
void xoayphai(TreeNode*&root)
{
    TreeNode*b=root;
    TreeNode*tmp=b->left;
    TreeNode*a=tmp->right;
    b->left=a;
    tmp->right=b;
    root=tmp;
}
void xoaytrai(TreeNode*&root)
{
    TreeNode*b=root;
    TreeNode*tmp=b->right;
    TreeNode*a=tmp->left;
    b->right=a;
    tmp->left=b;
    root=tmp;
}
int dosau(TreeNode*&root)
{
    if(root==nullptr) return 0;
    return max(dosau(root->left)+1,dosau(root->right)+1);
}
void xoay(TreeNode*&root)
{
   if(root!=nullptr)
   {
     if(abs(dosau(root->left)-dosau(root->right))>1)
     {
        if(dosau(root->left)>dosau(root->right))
        {
            if(dosau(root->left->left)>=dosau(root->left->right))
            {
                xoayphai(root);
            }
            else
            {
                xoaytrai(root->left);
                xoayphai(root);
            }
        }
        else
        {
            if(dosau(root->right->right)>=dosau(root->right->left))
            {
                xoaytrai(root);
            }
            else
            {
                xoayphai(root->right);
                xoaytrai(root);
            }
        }
     }
    xoay(root->left);
    xoay(root->right);
   }
}
    TreeNode* sortedListToBST(ListNode* head) {
        TreeNode*a=nullptr;
        TreeNode*tmp=nullptr;
        while(head!=nullptr)
        {
            if(a==nullptr)
            {
                a=new TreeNode(head->val);
                tmp=a;

            }
            else
            {
               tmp->right=new TreeNode(head->val);
               tmp=tmp->right;
            }
            head=head->next;
        }
        if(a!=nullptr)
        {
       while(abs(dosau(a->left)-dosau(a->right))>1)
       {
        xoay(a);
       }
        }
        return a;
    }
};
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