leetcode61~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.

对链表从右侧k个数进行翻转。
注意：k可以大于链表的长度，需要对链表长度取余

public class RotateList {
public ListNode rotateRight(ListNode head, int k) {
if(head==null || k<1) return head;
int count = 1;
ListNode cur = head;
while(cur.next!=null) {
cur = cur.next;
count++;
}
//此时cur指向最后一个节点
ListNode tail = cur;
//k可以大于链表长度
k = k%count;
if(k==0) return head;
int tmp = count - k;
//cur重新指向头节点
cur = head;
while((–tmp)!=0) {
cur =cur.next;
}
//此时cur指向要翻转节点的前一个节点
tail.next = head;
//对head重新赋值
head = cur.next;
cur.next = null;
return head;
}
}