61_rotate_list

# 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):
        """
        :type head: ListNode
        :type k: int
        :rtype: ListNode
        """
        
        slow = fast = curr = head
        node = None
        size = 0
        
        while curr:
            curr = curr.next
            size += 1
        

        if not head or not head.next or k == 0 or k%size == 0: return head
        
        for i in range(k%size):
            fast = fast.next
            
        while fast.next:
            fast = fast.next
            slow = slow.next
            
        fin = slow
        head_new = slow.next
    
        while slow.next:
            slow = slow.next
            
        slow.next = head
        fin.next = None
        
        return head_new
            b