[LeetCode] 61 Rotate List

/**
 * 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||head->next==NULL)return head;
        ListNode *tail,*pre;
        tail=pre=head;
        int len=1;
        while(tail->next!=NULL) //找到尾部
        {
            tail=tail->next;
            len++;
        }
        int i=len-(k%(len))-1;  //考虑k数据的过大
        while(i>0)
        {
            i--;
            pre=pre->next;
        }
        tail->next=head;
        head=pre->next;
        pre->next=NULL;
        return head;
    }
};