题目:

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]

代码实现:

class Solution {
public ListNode removeNthFromEnd(ListNode head, int n) {
ListNode dummy = new ListNode(0, head);
int length = getLength(head);
ListNode cur = dummy;
for (int i = 1; i < length - n + 1; ++i) {
cur = cur.next;
}
cur.next = cur.next.next;
ListNode ans = dummy.next;
return ans;
}

public int getLength(ListNode head) {
int length = 0;
while (head != null) {
++length;
head = head.next;
}
return length;
}
}