1650. Lowest Common Ancestor of a Binary Tree III

"""
# 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':
        a, b = p, q
        while a != b:
            a = a.parent if a.parent else q
            b = b.parent if b.parent else p
        return a