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:
    ListNode* removeNthFromEnd(ListNode* head, int n) {
        if (head == nullptr) return nullptr;
        ListNode* count_node = head;
        int count_n = 0;
        while (count_node) {
            count_node = count_node->next;
            count_n++;
        }
        int site_node = count_n-n;
        ListNode* now_node = head;
        if (site_node == 0 ) return head->next;
        while (now_node&&site_node>1) {
            now_node = now_node->next;
            site_node--;
        }
        if (now_node->next) {
            ListNode* nxt = now_node->next->next;
            now_node->next->next = nullptr;
            now_node->next = nxt;
        }
        return head;
    }
};