leetcode 70: Rotate List

Rotate ListMar
28 '12

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

.

/**
* Definition for singly-linked list.
* public class ListNode {
*     int val;
*     ListNode next;
*     ListNode(int x) {
*         val = x;
*         next = null;
*     }
* }
*/
public class Solution {
public ListNode rotateRight(ListNode head, int n) {
// Start typing your Java solution below
// DO NOT write main() function
if(head==null || n==0) return head;

ListNode p=head, q=head;
while( n-->0) {
q=q.next;
if( q==null) q=head;
}

if(q==head) return head;

while(q.next!=null){
q=q.next;
p=p.next;
}

ListNode temp = p.next;
q.next = head;
p.next = null;

return temp;
}
}