代码随想录算法训练营第四天|24. 两两交换链表中的节点 ，19.删除链表的倒数第N个节点 ，面试题 02.07. 链表相交， 142.环形链表II

day4 19.删除链表的倒数第N个节点

题目链接：leetcode.cn/problems/re…

这题主要是运用双指针的思路。 代码如下： /**

• 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* dummyHead = new ListNode(0); dummyHead->next = head; ListNode* slow = dummyHead; ListNode* fast = dummyHead; while(n-- && fast != NULL) { fast = fast->next; } fast = fast->next; while (fast != NULL) { fast = fast->next; slow = slow->next; } slow->next = slow->next->next;

   // ListNode *tmp = slow->next; 
   // slow->next = tmp->next;
   // delete tmp;
   
   return dummyHead->next;
  

  } };