-- coding:utf-8 --

class ListNode:

def init(self, x):

self.val = x

self.next = None

class Solution:
# 返回ListNode
def ReverseList(self, pHead):
# write code here
'''
#方法1：直接建立新的链表，然后使用头插法逆置
head=ListNode(0)
head.next=None
p=pHead
while p:
s=ListNode(p.val)
s.next=head.next
head.next=s
p=p.next
return head.next
'''
#方法2：直接使用头插法,在原表上进行逆置
head=ListNode(0)
head.next=None
p=pHead
while p:
s=p.next
p.next=head.next
head.next=p
p=s
return head.next