LeetCode之Remove Nth Node From End of List

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode(int x) : val(x), next(NULL) {}
 * };
 */
 /*用两个指针p,q，最开始都指向头结点，让p先走n个结点，然后p，q一起
 走，直到p走到尾结点。
 参考自：https://github.com/soulmachine/leetcode*/ 
class Solution {
public:
    ListNode *removeNthFromEnd(ListNode *head, int n) {
        ListNode newHead(-1);
        newHead.next = head;
        ListNode *p(&newHead), *q(&newHead);
        for(int i = 0; i < n; ++i) p = p->next;
        while(p->next != nullptr){
            p = p->next;
            q = q->next;
        }
        ListNode *tmp = q->next;
        q->next = q->next->next;
        delete tmp;
        return newHead.next;
    }
};