Delete-Last-Nth-Node

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

题目：
Given the head of a linked list, remove the nth node from the end of the list and return its head.

Example 1:

Input: head = [1,2,3,4,5], n = 2
Output: [1,2,3,5]

Example 2:

Input: head = [1], n = 1
Output: []

Example 3:

Input: head = [1,2], n = 1
Output: [1]

Constraints:

• The number of nodes in the list is sz.
• 1 <= sz <= 30
• 0 <= Node.val <= 100
• 1 <= n <= sz

解决了进阶问题： 一次循环解决问题

/**
 * 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) {
        if(head->next == nullptr) return nullptr;
        ListNode* temp = head;
        ListNode* tail = temp->next;
        for(int i = 1; i < n && tail != nullptr; i++) tail = tail->next;
        if(tail == nullptr){
            return head->next;
        }
        else{
            while(tail->next != nullptr) {
                temp = temp->next;
                tail = tail->next;
            }
            temp->next = temp->next->next;
            return head;
        }
        
   }
};