如何使用python实现随时间增加节点的数据结构

编程小白求指导，如何实现如图所示的数据结构，并且统计节点数

python实现链表
首先，定义节点类Node：
class Node:
'''
data: 节点保存的数据
next: 保存下一个节点对象
'''
def __init_(self, data, pnext=None):
self.data = data
self._next = pnext

def __repr__(self):
    '''
    用来定义Node的字符输出，
    print为输出data
    '''
    return str(self.data)
            然后，定义链表类：

链表要包括：

属性：

链表头：head

链表长度：length

方法：

判断是否为空: isEmpty()
def isEmpty(self):
return (self.length == 0
增加一个节点(在链表尾添加): append()
def append(self, dataOrNode):
item = None
if isinstance(dataOrNode, Node):
item = dataOrNode
else:
item = Node(dataOrNode)

if not self.head:
    self.head = item
    self.length += 1

else:
    node = self.head
    while node._next:
        node = node._next
    node._next = item
    self.length += 1
            删除一个节点: delete()
            #删除一个节点之后记得要把链表长度减一

def delete(self, index):
if self.isEmpty():
print "this chain table is empty."
return

if index < 0 or index >= self.length:
    print 'error: out of index'
    return
#要注意删除第一个节点的情况
#如果有空的头节点就不用这样
#但是我不喜欢弄头节点
if index == 0:
    self.head = self.head._next
    self.length -= 1
    return

#prev为保存前导节点
#node为保存当前节点
#当j与index相等时就
#相当于找到要删除的节点
j = 0
node = self.head
prev = self.head
while node._next and j < index:
    prev = node
    node = node._next
    j += 1

if j == index:
    prev._next = node._next
    self.length -= 1
            修改一个节点: update()
            def update(self, index, data):
if self.isEmpty() or index < 0 or index >= self.length:
    print 'error: out of index'
    return
j = 0
node = self.head
while node._next and j < index:
    node = node._next
    j += 1

if j == index:
    node.data = data
            查找一个节点: getItem()
            def getItem(self, index):
if self.isEmpty() or index < 0 or index >= self.length:
    print "error: out of index"
    return
j = 0
node = self.head
while node._next and j < index:
    node = node._next
    j += 1

return node.data
    查找一个节点的索引: getIndex()
    def getIndex(self, data):
j = 0
if self.isEmpty():
    print "this chain table is empty"
    return
node = self.head
while node:
    if node.data == data:
        return j
    node = node._next
    j += 1

if j == self.length:
    print "%s not found" % str(data)
    return
            插入一个节点: insert()
            def insert(self, index, dataOrNode):
if self.isEmpty():
    print "this chain tabale is empty"
    return

if index < 0 or index >= self.length:
    print "error: out of index"
    return

item = None
if isinstance(dataOrNode, Node):
    item = dataOrNode
else:
    item = Node(dataOrNode)

if index == 0:
    item._next = self.head
    self.head = item
    self.length += 1
    return

j = 0
node = self.head
prev = self.head
while node._next and j < index:
    prev = node
    node = node._next
    j += 1

if j == index:
    item._next = node
    prev._next = item
    self.length += 1
            清空链表: clear()
            def clear(self):
self.head = None
self.length = 0