leetcode之Lowest Common Ancestor of a Binary Search Tree

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

class Solution(object):
def lowestCommonAncestor(self, root, p, q):
"""
:type root: TreeNode
:type p: TreeNode
:type q: TreeNode
:rtype: TreeNode
"""
if p.val <= root.val <= q.val or p.val >= root.val >= q.val:
return root
if p.val < root.val and q.val < root.val:
return self.lowestCommonAncestor(root.left, p, q)
if q.val > root.val and p.val > root.val:
return self.lowestCommonAncestor(root.right, q, p)