leetcode109

这道题是leetcode108的升级版，先将单链表转化成数组，然后再根据数组生成高度平衡二叉搜索树。

 1 class Solution:
 2     def sortedArrayToBST(self, nums: List[int]) -> TreeNode:
 3         n = len(nums)
 4         if n == 0:
 5             return None
 6         if n == 1:
 7             return TreeNode(nums[0])
 8         mid = n // 2
 9         root = TreeNode(nums[mid])
10         root.left = self.sortedArrayToBST(nums[:mid])
11         root.right = self.sortedArrayToBST(nums[mid+1:])
12         return root
13     
14     def sortedListToBST(self, head: ListNode) -> TreeNode:
15         lists = []
16         while head != None:
17             lists.append(head.val)
18             head = head.next
19         root = self.sortedArrayToBST(lists)
20         return root