交叉链表求焦点，修改了一下后面那个解答是错误的

[lpdswing]

遍历完长链表直接就返回了肯定不对啊

[starrye]

    l1 = headA
    l2 = headB
    while l1 != l2:
        l1 = l1.next if l1 else headB
        l2 = l2.next if l2 else headA
    return l1