题目
Write a program to find the node at which the intersection of two singly linked lists begins.
解题思路
两个指针同时遍历两个链表，当到达一个尾骨之后，换到另一的头部继续遍历，两个指针会在链表的相交节点相遇
代码
class Solution:
def getIntersectionNode(self, headA: ListNode, headB: ListNode) -> ListNode:
if not headA or not headB:
return None
pa, pb = headA, headB
while pa is not pb:
pa = headB if pa is None else pa.next
pb = headA if pb is None else pb.next
return pa
