统计

    def ReverseList(self, pHead):
        # write code here
        if pHead == None or pHead.next == None:  # 若链表为空或者仅一个数就直接返回
            return pHead
        pre = None
        next = None
        while (pHead != None):
            next = pHead.next  # 1
            pHead.next = pre  # 2
            pre = pHead  # 3
            pHead = next  # 4
        return pre