16反转链表python

题目：输入一个链表，反转链表后，返回头结点
思路：先把下一个节点保存之后，将所有节点指向前一个节点

# -*- coding:utf-8 -*-# class ListNode:#     def __init__(self, x):#         self.val = x#         self.next = Noneclass Solution:    # 返回ListNode    def ReverseList(self, pHead):        # write code here        if pHead == None:            return None        pNode = pHead        pPrev = None        while pNode != None:            pNext  = pNode.next #将下一个节点保存至pNext            if pNext == None:#如果下个节点为空，则此处为反转后的链头                pReversedHead = pNode            pNode.next = pPrev            pPrev = pNode            pNode = pNext        return pReversedHead