2019年3月4日 701. Insert into a Binary Search Tree

比較基礎的二叉樹排序樹插入，寫了個遞歸。

# Definition for a binary tree node.
# class TreeNode(object):
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = Noneclass Solution(object):def insertIntoBST(self, root, val):""":type root: TreeNode:type val: int:rtype: TreeNode"""if root is None:return TreeNode(val)if val < root.val:root.left = self.insertIntoBST(root.left, val)else:root.right = self.insertIntoBST(root.right, val)return root