今天看了一下数据结构的书，发现其实数据结构没有几种，线性表，数组，字符串，队列和栈，等等，其实是一回事，然后就是树结构，图结构。数据结构的理论并不难，主要是要自己写一下这些数据结构以及对应的基本的操作方法，这样就能够更快的提高。
链表就失去了顺序表的随机存取特点，即每次从中取一个元素都要从头开始找，这样耗费了一些时间，时间复杂度为o(n)；但是在做插入和删除，以及两个链表合并的时候，就方便了很多，只需要做一点指针修改就可以了。
在很多语言中没有指针这一概念，而有数组的概念，比如java和python，java中的数组还要求定义数组的类型，也就是说必须都是同一类型的数据，而python则没有要求，所以python的list更贴近链表的真正含义。这种用数组描述的链表叫做静态链表。使用静态链表来描述链表对此类语言要方便很多了，本身这些语言都提供了内置类来处理链表。
# -*- coding=utf-8 -*-# 这个例子是Python版本的单链表class Node(object): def __init__(self, value, next=0): self.value = value self.next = next # 指针class LinkedList(object): # 链表的数据结构 def __init__(self): self.head = 0 # 头部 def __getitem__(self, key): if self.is_empty(): print 'Linked list is empty.' return elif key < 0 or key > self.get_length(): print 'The given key is wrong.' return else: return self.get_elem(key) def __setitem__(self, key, value): if self.is_empty(): print 'Linked list is empty.' return elif key < 0 or key > self.get_length(): print 'The given key is wrong.' return else: return self.set_elem(key, value) def init_list(self, data): # 按列表给出 data self.head = Node(data[0]) p = self.head # 指针指向头结点 print p, self.head for i in data[1:]: p.next = Node(i) # 确定指针指向下一个结点 p = p.next # 指针滑动向下一个位置 print self.head.next.next def get_length(self): length = 0 p = self.head while p != 0: # 0 值就是Node结点中默认的 0 值，表示下一个结点没有了，即没有为其赋值 length += 1 p = p.next return length def is_empty(self): if self.head == 0: return True else: return False def insert_node(self, index, value): if index < 0 or index > self.get_length(): print 'Can not insert node into the linked list.' elif index == 0: temp = self.head self.head = Node(value, temp) else: p, post = self.head, self.head for i in xrange(index): post = p p = p.next temp = p post.next = Node(value, temp) def delete_node(self, index): if index < 0 or index > self.get_length()-1: print "Wrong index number to delete any node." elif self.is_empty(): print "No node can be deleted." elif index == 0: temp = self.head self.head = temp.next elif index == self.get_length(): p = self.head for i in xrange(self.get_length()-2): p = p.next p.next = 0 else: p = self.head for i in xrange(index-1): p = p.next p.next = p.next.next def show_linked_list(self): # 打印链表中的所有元素 if self.is_empty(): print 'This is an empty linked list.' else: p, container = self.head, [] for _ in xrange(self.get_length()-1): container.append(p.value) p = p.next container.append(p.value) print container def clear_linked_list(self): # 将链表置空 self.head = 0 def get_elem(self, index): if self.is_empty(): print "The linked list is empty. Can not get element." elif index < 0 or index > self.get_length()-1: print "Wrong index number to get any element." else: p = self.head for _ in xrange(index): p = p.next return p.value def set_elem(self, index, value): if self.is_empty(): print "The linked list is empty. Can not set element." elif index < 0 or index > self.get_length()-1: print "Wrong index number to set element." else: p = self.head for _ in xrange(index): p = p.next p.value = value def get_index(self, value): p = self.head for i in xrange(self.get_length()): if p.value == value: return i else: p = p.next return -1l = LinkedList()print "The length of linked list now is: ", l.get_length()print l.is_empty()l.init_list([1, 5, 12, "fjd", 45, 999])print "The length of linked list now is: ", l.get_length()print l.is_empty()l.insert_node(4, 100)l.insert_node(6, "cecil")l.show_linked_list()print "The value of index 0 is: ", l.get_elem(0)l.set_elem(0,1000)l.show_linked_list()print "the index of *** is: ", l.get_index(1009)print "The length of linked list now is: ", l.get_length()l.delete_node(3)#l.clear_linked_list()l.show_linked_list()
