lintcode 容易题：Reverse Linked List 翻转链表

翻转链表

"""
Definition of ListNode

class ListNode(object):

def __init__(self, val, next=None):
self.val = val
self.next = next
"""
class Solution:
"""
@param head: The first node of the linked list.
@return: You should return the head of the reversed linked list.
Reverse it in-place.
"""
def reverse(self, head):
# write your code here
p = head
prev = None
revHead = None
while p!=None:
pNext = p.next
if pNext ==None:
revHead = p
p.next = prev
prev = p
p = pNext
return revHead