LeetCode——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.

原题链接：https://oj.leetcode.com/problems/rotate-list/

得到链表长度。链表指向尾节点，将链表首尾相连，向右k%len。得到结果链表的尾节点。

public class RotateList {
public static void main(String[] args) {
ListNode head = new ListNode(1);
ListNode head1 = new ListNode(2);
ListNode head2 = new ListNode(3);
ListNode head3 = new ListNode(4);
ListNode head4 = new ListNode(5);
head.next = head1;
head1.next = head2;
head2.next = head3;
head3.next = head4;
//while(head != null){
//System.out.println(head.val);
//head = head.next;
//}
ListNode ln = new RotateList().rotateRight(head, 2);
while(ln != null){
System.out.println(ln.val);
ln = ln.next;
}
}
public ListNode rotateRight(ListNode head, int n) {
if(head == null)
return head;
int len = 1;
ListNode tmp = head;
while(tmp.next != null){
tmp = tmp.next;
len ++;
}
tmp.next = head;
n %= len;
int step = len - n;
while(step > 0){
tmp = tmp.next;
step --;
}
head = tmp.next;
tmp.next = null;
return head;
}}
// Definition for singly-linked list.
 class ListNode {
int val;
ListNode next;ListNode(int x) {
val = x;
next = null;
}
}