LCA of binary tree

"""
# Definition for a Node.
class Node:
    def __init__(self, val):
        self.val = val
        self.left = None
        self.right = None
        self.parent = None
"""

class Solution:
    def lowestCommonAncestor(self, p: 'Node', q: 'Node') -> 'Node':

        # check whether p is descenet of q -> q
        # check whether q is descent of p -> p

        # check whether p descenet of q.parent -> q.parent
        # check wether q descent of p.parent ->


        def is_descendent(a, b):
            while a:
                if a == b:
                    return True
                a = a.parent
            return False

        if is_descendent(p, q):
            return q
        if is_descendent(q, p):
            return p

        return self.lowestCommonAncestor(p.parent, q.parent)