力扣19. 删除链表的倒数第 N 个结点

Posted 2021-06-26 幽殇默

题目地址

/**
 * 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) {
        int k=0;
        ListNode *a=new ListNode(-1); a->next=head;
        ListNode *b=a;
        while(a)
        {
            a=a->next;
            k++;
        }
        k--;
        int w=k-n;
        a=b;
        for(int i=1;i<=w;i++)
        {
            b=b->next;
        }
        b->next=b->next->next;
        return a->next;
    }
};