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数据结构是计算机科学必须掌握的一门学问，之前很多的教材都是用C语言实现链表，因为c有指针，可以很方便的控制内存，很方便就实现链表，其他的语言，则没那么方便，有很多都是用模拟链表，不过这次，我不是用模拟链表来实现，因为python是动态语言，可以直接把对象赋值给新的变量。

好了，在说我用python实现前，先简单说说链表吧。在我们存储一大波数据时，我们很多时候是使用数组，但是当我们执行插入操作的时候就是非常麻烦，看下面的例子，有一堆数据1,2,3,5,6,7我们要在3和5之间插入4,如果用数组，我们会怎么做？当然是将5之后的数据往后退一位，然后再插入4,这样非常麻烦，但是如果用链表，我就直接在3和5之间插入4就行，听着就很方便。

那么链表的结构是怎么样的呢？顾名思义，链表当然像锁链一样，由一节节节点连在一起，组成一条数据链。

链表的节点的结构如下：

data为自定义的数据，next为下一个节点的地址。

链表的结构为，head保存首位节点的地址：

接下来我们来用python实现链表

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

以上就是链表类的要实现的方法。

执行的结果：

接下来是完整代码：

# -*- coding:utf8 -*-

#/usr/bin/env python

class Node(object):

def __init__(self, data, pnext = None):

self.data = data

self._next = pnext

def __repr__(self):

return str(self.data)

class ChainTable(object):

def __init__(self):

self.head = None

self.length = 0

def isEmpty(self):

return (self.length == 0)

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

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

if index == 0:

self.head = self.head._next

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:

prev._next = node._next

self.length -= 1

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

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

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

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

def clear(self):

self.head = None

self.length = 0

def __repr__(self):

if self.isEmpty():

return "empty chain table"

node = self.head

nlist = ''

while node:

nlist += str(node.data) + ' '

node = node._next

return nlist

def __getitem__(self, ind):

if self.isEmpty() or ind < 0 or ind >= self.length:

print "error: out of index"

return

return self.getItem(ind)

def __setitem__(self, ind, val):

if self.isEmpty() or ind < 0 or ind >= self.length:

print "error: out of index"

return

self.update(ind, val)

def __len__(self):

return self.length