入门级别的面试题——LeetCode题目19：删除链表的倒数第N个节点

/**
 * Definition for singly-linked list.
 * struct ListNode {
 * int val;
 * ListNode *next;
 * ListNode(int x) : val(x), next(NULL) {}
 * };
 */

class Solution {
public:
    ListNode* removeNthFromEnd(ListNode* head, int n) {
        ListNode *dummy = new ListNode(-1);
        dummy->next = head;

        ListNode *p = dummy, *q = dummy;
        while (n) { q = q->next; --n; }

        while (q->next != NULL) {
            p = p->next;
            q = q->next;
        }

        ListNode *rm = p->next;
        p->next = p->next->next;
        head = dummy->next;

        delete(rm);
        delete(dummy);

        return head;
    }
};