本文实例讲述了Python数据结构与算法之链表定义与用法。分享给大家供大家参考，具体如下：

本文将为大家讲解：

(1)从链表节点的定义开始，以类的方式，面向对象的思想进行链表的设计

(2)链表类插入和删除等成员函数实现时需要考虑的边界条件，

prepend(头部插入)、pop(头部删除)、append(尾部插入)、pop_last(尾部删除)

2.1 插入：

空链表

链表长度为1

插入到末尾

2.2 删除

空链表

链表长度为1

删除末尾元素

(3)从单链表到单链表的一众变体：

带尾节点的单链表

循环单链表

双链表

1. 链表节点的定义

class LNode:

def __init__(self, elem, next_=None):

self.elem = elem

self.next = next_

2. 单链表的实现

重点理解插入、删除的实现及其需要考虑的边界条件：

class LinkedListUnderflow(ValueError):

pass

class LList:

def __init__(self):

self._head = None

def is_empty(self):

return self._head is None

def prepend(self, elem):

self._head = LNode(elem, self._head)

def pop(self):

if self._head is None:

raise LinkedListUnderflow('in pop')

e = self._head.elem

self._head = self._head.next

return e

def append(self, elem):

if self._head is None:

self._head = LNode(elem)

return

p = self._head

while p.next is not None:

p = p.next

p.next = LNode(elem)

def pop_last(self):

if self._head is None:

raise LinkedListUnderflow('in pop_last')

p = self._head

if p.next is None:

e = p.elem

self._head = None

return e

while p.next.next is not None:

p = p.next

e = p.next.elem

p.next = None

return e

简单总结：

(0)能够访问 p.next.next 的前提是 p.next 不为空；

(1)尾部插入，如果链表不为空，需且仅需改变的是尾部节点的指针；

(2)尾部删除，如果链表长度不为空，需且仅需改变的是倒数第二个节点的指针。

单链表的简单变形：具有尾部节点的单链表

class LList1(LList):

def __init__(self):

LList.__init__(self)

self._rear = None

...

我们仅需重写的是：头部的插入、尾部的插入、尾部的删除

def prepend(self, elem):

if self._head is None:

self._head = LNode(elem)

self._rear = self._head

else:

self._head = LNode(elem, self._head)

def append(self, elem):

if self._head is None:

self._head = LNode(elem)

self._rear = self._head

else:

self._rear.next = LNode(elem)

self._rear = self._rear.next

def pop_last(self):

if self._head is None:

raise LinkedListUnderflow('in pop_last')

p = self._head

if p.next is None:

e = p.elem

self._head = None

return e

while p.next.next is not None:

p = p.next

e = p.next.elem

self._rear = p

p.next = None

return e

单链表的变体：循环单链表

class LCList:

def __init__(self):

self._rear = None

def prepend(self, elem):

if self._rear is None:

self._rear = LNode(elem)

self._rear.next = self._rear

else:

self._rear.next = LNode(elem, self._rear.next)

def append(self, elem):

self.prepend(elem)

self_rear = self._rear.next

def pop(self):

if self._rear is None:

raise LinkedListUnderflow('in pop')

p = self._rear.next

if p is None:

self._rear = None

else:

self._rear.next = p.next

return p.elem

def printall(self):

if self._rear is None:

raise ...

p = self._rear.next

while True:

print(p.elem)

if p is self._rear:

break

p = p.next

希望本文所述对大家Python程序设计有所帮助。