LeetCode 面试经典150题 [60/150 删除链表的倒数第N个结点]

题目描述

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：[]

个人C++解答

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode() : val(0), next(nullptr) {}
 *     ListNode(int x) : val(x), next(nullptr) {}
 *     ListNode(int x, ListNode *next) : val(x), next(next) {}
 * };
 */
class Solution {
public:
    ListNode* removeNthFromEnd(ListNode* head, int n) {
        ListNode* result = new ListNode();
        ListNode *p = head, *q = result;
        int len = 0, count = 0;
        while (p) {
            len++;
            p = p->next;
        }
        p = head;
        while (p) {
            count++;
            if (count == (len - n + 1))
                break;
            q->next = p;
            p = p->next;
            q = q->next;
        }
        p = p->next;
        q->next = p;
        return result->next;
    }
};