1650. Lowest Common Ancestor of a Binary Tree III

This is just like question for finding the intersection of two linked lists. You keep iterating and then reset to the other pointer.

class Solution:
    def lowestCommonAncestor(self, p: 'Node', q: 'Node') -> 'Node':
        p1, p2 = p, q
        while p1 != p2:
            p1 = p1.parent if p1.parent else q
            p2 = p2.parent if p2.parent else p
        return p1