leetcode-----19. 删除链表的倒数第N个节点

• 链接：https://leetcode-cn.com/problems/remove-nth-node-from-end-of-list/

代码

/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode(int x) { val = x; }
 * }
 */
class Solution {
    public ListNode removeNthFromEnd(ListNode head, int n) {
        ListNode dummy = new ListNode(0);
        dummy.next = head;

        ListNode first = dummy;
        ListNode second = dummy;

        for (int i = 0; i <= n; ++i) first = first.next;
        while (first != null) {
            first = first.next;
            second = second.next;
        }
        second.next = second.next.next;
        return dummy.next;
    }
}