Python数据结构的实现

1 . 链表
python中，使用类的嵌套实现链表。
节点和链表都用类来表示。节点有两个变量data和next，data存储数据，next为下一个节点。链表有一个变量head，将node赋给head。

#!/usr/bin/python# coding: utf-8class Node(object):    def __init__(self,value,pointer=0):        self.data = value        self.next = pointerclass LinkList(object):    def __init__(self):        self.head = 0    def initlist(self, data):        self.head = Node(data[0])        temp = self.head        for i in data[1:]:            node = Node(i)            temp.next = node            temp = temp.next    def length(self):                p = self.head        length = 0        while p != 0:            length += 1             p = p.next        return length    def empty(self):        if self.length() == 0:            return True        else:            return False    def clear(self):        self.head = 0    def append(self, item): #append item in the end of LinkList        new_node = Node(item)        if self.head == 0:            self.head = new_node        else:            temp = self.head            while temp.next != 0:                temp = temp.next            temp.next = new_node    def getitem(self, index):   # index is the No.number of the Linked_list        if self.empty():            print 'LinkList is empty.'            return None        elif index < 0 or index >= self.length():            print 'The index is out of the LinkList.'            return None        counter = 0        temp = self.head        while temp.next != 0 and counter<index:            temp = temp.next            counter += 1        if counter == index:            return temp.data        else:            print 'target is not exist!'    def insert(self, index, item):  # insert item in the middle of the LinkList        if self.empty():            print 'LinkList is empty.'            return None        elif index > self.length():            print 'The index is out of the LinkList.'            return None        if index == 0:            self.head = Node(item, self.head)            return None        temp = self.head        for i in range(index-1):            temp = temp.next        if temp.next == 0:            temp.next = Node(item)        else:            old_item = temp.next            temp.next = Node(item)            temp.next.next = old_item        return None    def delete(self, index):        if self.empty() or index < 0 or index >= self.length():            print 'Index is out of the range'            return None        if index == 0:            self.head = self.head.next        temp = self.head        for i in range(index-1):            temp = temp.next        if temp.next.next == 0:            temp.next =0        else:            temp.next = temp.next.next    def index(self, value):        if self.empty():            print 'LinkList is empty.'            return None        temp = self.head        counter = 0        while temp.next != 0:            if temp.data == value:                return counter            counter += 1            temp = temp.next        return 'No value!'

单向循环链表
双向链表

2 . 栈

#!/usr/bin/env python# coding: utf-8class Stack(object):    def __init(self):        self.stack = []    def push(self, item):        self.stack.append(item)    def pop(self):        if self.stack != []:            self.stack.pop()        else:            return None    def head(self):        if self.stack != []:            return self.stack[0]        else:            return None    def tail(self):        if self.stack != []:            return self.stack[-1]        else:            return None    def length(self):        return len(self.stack)    def empty(self):        return self.stack == []

3 . 队列

python对队列有现成的库Queue。

>import Queue>q = Queue.Queue()>q.put(1)>q.put(2)>q.empty()False>q.get()1>q.get()2

注意，在队列空的时候调用get()，解释器就会崩溃（win python2.7），暂时没有解决办法。

用列表写的队列如下：

#!/usr/bin/env python# coding: utf-8class Queue(object):    def __init__(self):        self.queue = []    def enqueue(self, item):        self.queue.append(item)    def dequeue(self):        if self.queue != []:            return self.queue.pop(0)        else:            return None    def head(self):        if self.queue != []:            return self.queue[0]        else:            return None    def tail(self):        if self.queue != []:            return self.queue[-1]        else:            return None    def length(self):        return len(self.queue)    def empty(self):        return self.queue == []