为什么可以';我不能在Python中获取linkdeque中节点的值吗?
问题是: 当我在python中尝试这一点时:为什么可以';我不能在Python中获取linkdeque中节点的值吗?,python,linked-list,deque,Python,Linked List,Deque,问题是: 当我在python中尝试这一点时: class _DoublyLinkedBase: class _Node: __slots__ ="_element", "_prev", "_next" def __init__(self, element, prev, next): self._element = element self._prev = prev self._nex
class _DoublyLinkedBase:
class _Node:
__slots__ ="_element", "_prev", "_next"
def __init__(self, element, prev, next):
self._element = element
self._prev = prev
self._next = next
def __init__(self):
self._header = self._Node(None, None, None)
self._trailer = self._Node(None, None, None)
self._header._next = self._trailer
self._trailer._prev = self._header
self._size = 0
def __len__(self):
return self._size
def is_empty(self):
return self._size == 0
def _insert_between(self, e, predecessor, successor):
newest = self._Node(e, predecessor, successor)
predecessor._next = newest
successor._prev = newest
self._size += 1
return newest
def _delete_node(self, node):
predecessor = node._prev
successor = node._next
predecessor._next = successor
successor._prev = predecessor
self._size -= 1
element = node._element
node._prev = node._next = node._element = None
return element
class LinkedDeque(_DoublyLinkedBase):
def first(self):
if self.is_empty():
raise Empty("Deque is empty")
return self._header._next._element
def last(self):
if self.is_empty():
raise Empty("Deque is empty")
return self._trailer._prev._element
def insert_first(self, e):
self._insert_between(e, self._header, self._header._next)
def insert_last(self, e):
self._insert_between(e, self._trailer._prev, self._trailer)
def delete_first(self):
if self.is_empty():
raise Empty("Deque is empty")
return self._delete_node(self._header._next)
def delete_last(self):
if self.is_empty():
raise Empty("Deque is empty")
return self._delete._node(self._trailer._prev)
a=linkedque()##创建一个链接的数据块
b=_双链接数据库。_节点(5,无,无)35;#创建一个节点
a、 插入_first(b)35;#将b放在第一位
a、 首先()检查元素
出[42]:
为什么输出不是5?您的
insert\u first
方法希望传入一个元素,而不是\u Node类型的对象(它将自己将元素包装在\u Node
中)。因此,将初始化的b
替换为:
a = LinkedDeque() ## create a linked deque
b = _DoublyLinkedBase._Node(5, None, None) ## create a node
a.insert_first(b) ##put b in the first place
a.first() ##check the element
Out[42]: <_DoublyLinkedBase._Node instance at 0x117660830>
所列代码上的缩进有问题为什么要嵌套类?这使得您的代码不必要地令人讨厌,无法理解,也没有给您带来任何好处……哦,这些代码是从Python中的数据结构和算法一书中复制的。
b = 5 # Initialize an element.