# 160. Intersection of Two Linked Lists

## Description
Given the heads of two singly linked-lists headA and headB, return the node at which the two lists intersect. If the two linked lists have no intersection at all, return null.

## Solution

- Step1
Create a set() called same to check that if same node has been seen
- Step2
Traverse two linked-list and check the set to see weather it has already been visited

class Solution:
    def getIntersectionNode(self, headA: ListNode, headB: ListNode) -> Optional[ListNode]:
        same = set()
        cur1 = headA
        cur2 = headB

        while cur1:
            same.add(cur1)
            cur1 = cur1.next
        while cur2:
            if cur2 in same:
                return cur2
            else:
                same.add(cur2)
                cur2 = cur2.next

        return

## Complxity
Time complexity : O(N)