算法-快慢指针

func removeNthFromEnd(head *ListNode, n int) *ListNode {
    // 快慢指针
    dummy := &ListNode{}
    dummy.Next = head
    s, f := dummy, dummy

    // faster向前走n+1步，一会可以让slow停在想要删除的节点的前继节点上
    for n >= 0 && f != nil {
        f = f.Next
        n--
    }

    for f != nil {
        f = f.Next
        s = s.Next
    }

    s.Next = s.Next.Next
    return dummy.Next
}