class LinkNode(object):
    def __init__(self, data, p = None):
        self.data = data
        self.next = p

class LinkList(object):
    def __init__(self):
        self.head = None

    #链表初始化函数，尾插法，插入data
    def initlist_tail(self, data):
        #创建头结点，其实是第一个有值节点
        self.head = LinkNode(data[0])
        p = self.head
        for i in data[1:]:
            #print(i)
            node = LinkNode(i)
            p.next = node
            p = p.next

    #判断链表是否为空
    def isEmpty(self):
        p = self.head
        if p.next == None:
            print('The LinkList is Empty')
            return 1 #感觉是为了方便后续调用
        else:
            #print('The LinkList is not Empty')
            return 0

    #遍历链表并输出,用','隔开
    def ReadList(self):
        if self.isEmpty():
            exit(0)
        p = self.head
        while p:
            print(p.data, end = ',')
            p = p.next
        print('')

    #取链表长度
    def getLength(self):
        if self.isEmpty():
            exit(0)
        p = self.head
        lenth = 0
        while p:
            #print(p.data, end = ',')
            lenth += 1
            p = p.next
        print('lenth of the LinkList:', lenth)
        return lenth

    #在索引值为 index 的结点后插入结点key
    def insertElem(self, key, index):
        p = self.head
        j = 1
        while p and j < index:
            p = p.next
            j += 1
        if(p == 0 or j > index): #若出错则退出
            exit(0)
            print('insert error')
        node = LinkNode(key)
        node.next = p.next
        p.next = node
        print('inserted LinkList:')
        self.ReadList()

    #删除第 index个 结点后的那一个节点
    def deleteElem(self, index):
        p = self.head
        j = 1
        while p and j < index:
            p = p.next
            j += 1
        if(p == 0 or j > index): #若出错则退出
            exit(0)
            print('insert error')
        q = p.next
        p.next = q.next
        print('deleted LinkList:')
        self.ReadList()

    #链表逆序
    def reverseList(self):
        pre, next, current = None, None, None
        current = self.head
        # 当前节点指向头节点
        next = current.next
        # next 指向当前节点的下一个节点，即将后面的节点存储起来
        current.next = None
        # 令当前节点的next 指向None，即设为最后一个节点
        pre = current
        # 当前节点的前一个节点为当前节点
        current = next
        # 当前节点指向下一个节点开始下一轮循环
        while current.next != None:
            next = current.next
            # 存储后面的链表
            current.next = pre
            # 将原本的前面的链表设为后面的
            pre = current
            current = next
            # 遍历到链表最后一个节点时候，将其指向前驱节点
        current.next = pre
        # 头节点指向原来链表的最后一个节点
        self.head = current


data1 = [1, 2, 3, 4, 5]
data2 = [2, 0]
a = LinkList()
a.initlist_tail(data1)
a.reverseList()
a.ReadList() #输出结果为1,2,3,4,5,
a.getLength() #输出结果为lenth of the LinkList: 5
a.insertElem(6,3) #输出结果为1,2,3,6,4,5,
a.deleteElem(3)#1,2,3,4,5,