类似题:https://www.cnblogs.com/panweiwei/p/13585987.html
class Solution(object):
def lowestCommonAncestor(self, root, p, q):
"""
:type root: TreeNode
:type p: TreeNode
:type q: TreeNode
:rtype: TreeNode
"""
# 先特判
if not root:
return None
if p.val == q.val:
return p
# 再遍历
while root:
if p.val < root.val and q.val < root.val:
root = root.left
elif p.val > root.val and q.val > root.val:
root = root.right
else:
return root