# 【LeetCode】109. Convert Sorted List to Binary Search Tree 解题报告（Python）

# 题目描述：

Given a singly linked list where elements are sorted in ascending order, convert it to a height balanced BST.

For this problem, a height-balanced binary tree is defined as a binary tree in which the depth of the two subtrees of every node never differ by more than 1.

Example:

Given the sorted linked list: [-10,-3,0,5,9],

One possible answer is: [0,-3,9,-10,null,5], which represents the following height balanced BST:

``````      0
/ \
-3   9
/   /
-10  5
``````

# 解题方法

``````# Definition for singly-linked list.
# class ListNode:
#     def __init__(self, x):
#         self.val = x
#         self.next = None

# Definition for a binary tree node.
# class TreeNode:
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None

class Solution:
"""
:rtype: TreeNode
"""
nums = []
return self.helper(nums)

def helper(self, nums):
if not nums: return None
_len = len(nums)
mid = _len // 2
root = TreeNode(nums[mid])
root.left = self.helper(nums[:mid])
root.right = self.helper(nums[mid+1:])
return root
``````

# 日期

2018 年 6 月 23 日 ———— 美好的周末要从刷题开始