从整数列表创建二分搜索树

class TreeNode:
    def __init__(self, value):
        self.value = value
        self.left = None
        self.right = None

def insert(root, value):
    if root is None:
        return TreeNode(value)
    if value < root.value:
        root.left = insert(root.left, value)
    else:
        root.right = insert(root.right, value)
    return root

def create_bst(nums):
    root = None
    for num in nums:
        root = insert(root, num)
    return root

nums = [5, 2, 8, 1, 3, 6, 9]
bst = create_bst(nums)