剑指Offer-- 翻转链表 （python版）

# -*- 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
        pReversedHead = None  # 返回结果节点
        curNode = pHead       # 记录当前节点
        preNode = None        # 记录前一个节点
        while curNode != None:
            nextNode = curNode.next  # 记录下一个节点
            if nextNode == None:     # 若是最后一个节点，则返回这个节点
                pReversedHead = curNode
            curNode.next = preNode
            
            preNode = curNode
            curNode = nextNode
        return pReversedHead