python链接

class node:
    def __init__(self,data=None):
        self.data = data
        self.next = None

class link:
    def __init__(self):
        self.head = None

    def append(self,node):
        if self.head is None:
            self.head = node
            return
        lastnode = self.head
        while(lastnode.next!=None):
            lastnode = lastnode.next
        lastnode.next = node
        return

    def insert(self,node,index):
        if len(self)<=index:
            raise RuntimeError("长度异常")
        leftnode = None
        headnode = self.head
        for i in range(index):
            leftnode = headnode.next
        rightnode = leftnode.next
        leftnode.next = node
        node.next = rightnode
        return

    def addfirst(self,node):
        head = self.head
        self.head = node
        node.next = head
        return

    def del_node(self,data):
        node = self.head
        #删除head节点
        if node.data == data:
            self.head = node.next
            return
        #删除尾部节点
        for i in range(len(self)):
            if node.next.data == data and node.next.next==None:
                node.next = None
                return
        #删除中间节点
        for i in range(len(self)):
            if node.next.data == data:
                node.next = node.next.next
                return
            node = node.next
        return


    def __len__(self):
        if self.head==None:
            return 0
        else:
            lenth = 1
            node = self.head
            while(node.next!=None):
                lenth+=1
                node = node.next
            return lenth

    def print(self):
        node = self.head
        for i in range(len(self)):
            print(node.data)
            node = node.next
        return