一、题目

二、代码

/** * 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) {
    
     

     ///统一链表格式
    ListNode* dummyhead = new ListNode(0);  //设置虚假的头结点 为了使得单节点和多节点情况统一 
    dummyhead->next = head;

    ListNode* process_node = new ListNode(0); 
    process_node=dummyhead;


     int the_sum_of_the_node=0;
     while(head!=nullptr)
     {
    
        the_sum_of_the_node+=1;
        head=head->next;
     }
    
     std::cout<<"the_sum_of_the_node "<< the_sum_of_the_node <<std::endl;

     int the_number_of_the_delete=the_sum_of_the_node+1-n;

    std::cout<<"the_number_of_the_delete "<< the_number_of_the_delete <<std::endl;


    int count_the_number=1;
    while(count_the_number<the_number_of_the_delete)
    {
    
       count_the_number=count_the_number+1;
       process_node=process_node->next;
    }
    //跳出时，process_node应该正好指向需要删除的节点前一个
    process_node->next=process_node->next->next;

     return dummyhead->next;
     
    }
};

三、运行结果