🟡 剑指 Offer II 021. 删除链表的倒数第 n 个结点

LeetCode 提示

题目难度 中等

原题链接 🔗 leetcode

题解1

注意边界情况

/** * Definition for singly-linked list. * public class ListNode { *     int val; *     ListNode next; *     ListNode() {} *     ListNode(int val) { this.val = val; } *     ListNode(int val, ListNode next) { this.val = val; this.next = next; } * } */class Solution {    public ListNode removeNthFromEnd(ListNode head, int n) {        ListNode pre = head;        ListNode mock = new ListNode();        mock.next = head;        for (int i=0; pre != null && i<n; i+=1) {            pre = pre.next;        }        ListNode cur = mock;        while (pre != null) {            pre = pre.next;            cur = cur.next;        }        ListNode ans = cur.next;        cur.next = ans.next;        ans.next = null;                return mock.next;    }}