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* new_head = new ListNode(-1);
        new_head->next = head;

        ListNode* fast = new_head;
        for (int i = 0; i < n; i++) {
            fast = fast->next;
        }

        ListNode* slow = new_head;
        ListNode* pre_slow = nullptr;
        while (fast) {
            fast = fast->next;
            pre_slow = slow;
            slow = slow->next;
        }

        pre_slow->next = slow->next;

        return new_head->next;
    }
};