题解 | #删除链表的倒数第n个节点#

/**
 * struct ListNode {
 *	int val;
 *	struct ListNode *next;
 *	ListNode(int x) : val(x), next(nullptr) {}
 * };
 */
class Solution {
public:
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     *
     * 
     * @param head ListNode类 
     * @param n int整型 
     * @return ListNode类
     */
    ListNode* removeNthFromEnd(ListNode* head, int n) {
        // write code here
        ListNode *fast = head;
        ListNode *slow = head;
        ListNode *pre = head;

        if(!head)
        {
            return nullptr;
        }

        if(n == 0)
        {
            return head;
        }

        while(n--)
        {
            fast = fast->next;
        }

        while(fast)
        {
            fast = fast->next;
            pre = slow;
            slow = slow->next;
        }

        pre->next = slow->next;
        if(slow == head)
        {
            return head->next;
        }
        delete slow;


        return head;

    }
};