__author__ = 'cfwloader'

# Definition for singly-linked list.

class ListNode(object):

def __init__(self, x):

self.val = x

self.next = None

class Solution(object):

def removeNthFromEnd(self, head, n):

"""

:type head: ListNode

:type n: int

:rtype: ListNode

"""

if head is None:

return head

if n == 1:

node = head.next

if node is None:

return node

preNode = head

while node.next is not None:

preNode = node

node = node.next

preNode.next = None

return head

dict = {}

index = 1

iterator = head

while iterator is not None:

dict[index] = iterator

iterator = iterator.next

index += 1

target = dict[index - n]

if target == head:

return target.next

else:

dict[index - n - 1].next = target.next

return head

if __name__ == '__main__':

'''

[1,2,3]

2

'''