1 # Definition for singly-linked list. 2 # class ListNode(object): 3 # def __init__(self, x): 4 # self.val = x 5 # self.next = None 6 7 class Solution(object): 8 def removeNthFromEnd(self, head, n): 9 """ 10 :type head: ListNode 11 :type n: int 12 :rtype: ListNode 13 """ 14 if not head: 15 return None 16 dummy=ListNode(-1) 17 dummy.next=head 18 19 for i in range(n): 20 if(head): 21 head=head.next 22 else: 23 return None 24 25 if(head==None): 26 return dummy.next.next 27 28 slow=dummy.next 29 while(head.next): 30 head=head.next 31 slow=slow.next 32 33 slow.next=slow.next.next 34 35 return dummy.next