[LeetCode] 160. Intersection of Two Linked Lists

Problem : https://leetcode.com/problems/intersection-of-two-linked-lists/

Hash table based solution:

Time Complexity = O ( M + N )

# Definition for singly-linked list.
# class ListNode(object):
#     def __init__(self, x):
#         self.val = x
#         self.next = None

class Solution(object):
    def getIntersectionNode(self, headA, headB):
        """
        :type head1, head1: ListNode
        :rtype: ListNode
        """
        
        memo = set()

        p1 = headA
        p2 = headB

        while p1:
            memo.add(p1)
            p1 = p1.next

        while p2:
            if p2 in memo:
                return p2

            p2 = p2.next

        return None