19.删除链表的倒数第N个节点

Posted 2022-12-03 小刘你最强

给你一个链表，删除链表的倒数第 n 个结点，并且返回链表的头结点。

示例 1：

输入：head = [1,2,3,4,5], n = 2
输出：[1,2,3,5]
示例 2：

输入：head = [1], n = 1
输出：[]
示例 3：

输入：head = [1,2], n = 1
输出：[1]

class Solution 
    public ListNode removeNthFromEnd(ListNode head, int n) 
        ListNode dummy = new ListNode(-1, head);
        ListNode fast = dummy;
        ListNode slow = dummy;
        while(n-- > 0) 
            fast = fast.next;
        
        fast = fast.next;
        while(fast != null) 
            fast = fast.next;
            slow = slow.next;
        
        slow.next = slow.next.next;
        return dummy.next;