61. Rotate List （旋转链表）

题目链接：https://leetcode.com/problems/rotate-list/description/

题目大意：给一个链表，将其旋转K次得到最终链表

题解：显然是个要求循环节的问题，求好后先将需要翻转的那部分加入新的链表中，再将剩余（即头结点）后的加入，需要注意最终的终止条件是NULL

= =、最近要准备面试的东西，还是得多写点题

/** * Definition for singly-linked list. * struct ListNode { *     int val; *     ListNode *next; *     ListNode(int x) : val(x), next(NULL) {} * }; */class Solution {public:    int calcu(ListNode* head)    {        int n = 0 ;        while(head)        {            n++;            head = head->next;        }        return n;    }    ListNode* rotateRight(ListNode* head, int k) {        ListNode *p = head ;        ListNode *newlist = new ListNode(0);        ListNode *list = newlist;        int cnt = calcu(head);        if(cnt==0) return NULL;        if(cnt==1) return head;        k = k%cnt;        for(int i = 0 ; i < cnt-k ; i++)         {            p = p->next;        }        for(int i = 0 ; i < k ; i++)         {            list->next = p ;            cout<<list->next->val<<" ";            list = list->next;            p = p->next;        }        cout<<endl;        for(int i = 0 ; i < cnt-k;i++)        {            list ->next = head;            cout<<list->next->val<<" ";            head = head->next;            list = list->next;        }        cout<<endl;        list->next = NULL;        newlist = newlist->next;        return newlist;    }};