<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:
    unordered_map<TreeNode*, int> height;
    int get_height(TreeNode* t) {
        if (!t) return -1;
        return height[t];
    }

    void update_height(TreeNode* t) {
        height[t] = max(get_height(t->left), get_height(t->right))+1;
    }

    TreeNode* rotate(TreeNode* A) {
        auto B = A->right;
        A->right = B->left;
        B->left = A;
        update_height(A);
        update_height(B);
        return B;
    }

    TreeNode* insert(TreeNode* root, int val) {
        if (!root) {
            auto newNode = new TreeNode(val);
            height[newNode] = 0;
            return newNode;
        }
        root->right = insert(root->right, val);
        if (abs(get_height(root->left) - get_height(root->right)) >= 2) {
            root = rotate(root);
        }
        update_height(root);
        return root;
    }

    TreeNode* sortedListToBST(ListNode* head) {
        auto ptr = head;
        TreeNode* res = nullptr;
        while (ptr) {
            res = insert(res, ptr->val);
            ptr = ptr->next;
        }
        return res;
    }
};
28100