# class TreeNode:
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None
#
# 代码中的类名、方法名、参数名已经指定,请勿修改,直接返回方法规定的值即可
#
# 
# @param root TreeNode类 
# @param p int整型 
# @param q int整型 
# @return int整型
#
class Solution:
    def lowestCommonAncestor(self , root: TreeNode, p: int, q: int) -> int:
        # write code here
        """
        三种情况分类
        """
        # 保证p<q 
        if p>q:
            temp=p
            p=q
            q=temp 
        if root.val >=p and root.val<=q:
            return root.val # 找到
        elif root.val>q and root.val>p:
            return self.lowestCommonAncestor(root.left,p,q)
        elif root.val<q and root.val <p:
            return self.lowestCommonAncestor(root.right,p,q)