061. Rotate List

#!/usr/bin/env python3

__author__ = 'Wei Mu'

# Definition for singly-linked list.
# class ListNode:
#     def __init__(self, x):
#         self.val = x
#         self.next = None

class Solution:
    def rotateRight(self, head: 'ListNode', k: 'int') -> 'ListNode':
        if head == None or k == 0:
            return head
        
        pointer = head
        length = 1
        
        while pointer.next != None:
            length += 1
            pointer = pointer.next
        
        k = k % length
        
        if length == 1 or k == 0:
            return head
        
        
        start = ListNode(0)
        end_Node = pointer
        pointer2 = head
        
        for i in range(length-k):
            pointer = pointer2
            pointer2 = pointer2.next
            
        start.next = pointer2
        pointer.next = None
        end_Node.next = head
        
        return start.next