'''

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.

class ListNode(object):

def __init__(self, x):

self.val = x

self.next = None

class Solution(object):

def rotateRight(self, head, k):

ref = head

length = 0

while head:

head = head.next

length += 1

if length < 2 or k % length == 0:

return ref

prev = None

current = ref

for _ in xrange(length - (k % length)):

prev, current = current, current.next

prev.next = None

new_head = current

if not current:

return ref

while current.next:

current = current.next

current.next = ref

return new_head