Rotate List

k>length求链表长度，最后节点指向头节点。

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode(int x) : val(x), next(NULL) {}
 * };
 */
class Solution {
public:
    ListNode *rotateRight(ListNode *head, int k) {
        if(head == NULL){
            return NULL;
        }
        int lengthOfList = 0;
        ListNode *back = head, *front = head, *p = head;
        while(p->next != NULL){
            lengthOfList++;
            p = p->next;
        }
        lengthOfList++;
        p->next = head;
        k = lengthOfList - k%lengthOfList;
        while(--k){
            front = front->next;
        }
        ListNode *rotateHead = front->next;
        front->next = NULL;
        return rotateHead;
    }
};