Rotate List

Given a list, rotate the list to the right by k places, where k is non-negative.

For example:
Given 1->2->3->4->5->NULL and k = 2,
return 4->5->1->2->3->NULL.

一个小错误, 简直可以说是笔误, 浪费我近两个小时

悲夫~

启示:

当判断是否为NULL,时

如果是指针, 写成NULL == p 形式

如果是整形, 写成0 == n;

 while(!np->next) 这里不是!, 去掉!

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode(int x) : val(x), next(NULL) {}
 * };
 */
class Solution {
public:
    /*ListNode *kthNode(ListNode *head, int k)
    {
        if(!head||k==0||!head->next)
            return head;
        ListNode *np = head;
        ListNode *temp;
        int len = 1;
        while(!np->next)
        {
            len++;
            np = np->next;
        }
        np->next = head;
        k = k%len;
        k = len - k ;
        while(k--)
            np = np->next;
        temp = np->next;
        np->next = NULL;
        return temp;
        
    }
    */
    ListNode *rotateRight(ListNode *head, int k) {
       if(!head||k==0||!head->next)
            return head;
        ListNode *np = head;
        ListNode *temp;
        int len = 1;
        while(np->next)
        {
            len++;
            np = np->next;
        }
        np->next = head;
        k = k%len;
        k = len - k ;
        while(k--)
            np = np->next;
        temp = np->next;
        np->next = NULL;
        return temp;
        
    }
};