描述：用Python实现单链表，双链表，单循环链表，双循环链表
单链表的实现（链表的基本方法）：
1 # _*_ coding: utf-8 _*_ 2 # Filename: singlelinklist 3 # Function: create linklist datastructure 4 # Author: Latup 5 6 7 class Node(): 8 """define the node of linklist""" 9 10 def __init__(self, data=None, next=None): 11 self.data = data 12 self.next = next 13 14 15 class LinkList(): 16 """define class of linklist""" 17 18 def __init__(self): 19 self.head = Node() 20 self.length = 0 21 22 def init_linklist(self, data): 23 """initial linklist""" 24 25 p = self.head 26 for i in data: 27 node = Node(i) 28 p.next = node 29 p = p.next 30 self.length += 1 31 32 def isEmpty(self): 33 """Determine if the linklist is empty""" 34 return self.length == 0 35 36 def insert(self, _index, data): 37 """Insert an element into the linklist""" 38 39 if _index < 1 or _index > self.length+1: 40 print('IndexError: out of index, fail to insert') 41 return 42 p = self.head 43 node = Node(data) 44 count = 0 45 while count < _index-1: 46 p = p.next 47 count += 1 48 node.next = p.next 49 p.next = node 50 self.length += 1 51 52 def delt(self, _index): 53 """Delete the value of the element corresponding to _index""" 54 55 if _index < 1 or _index > self.length: 56 print('IndexError: out of index, fail to delt') 57 return 58 p = self.head 59 count = 0 60 while count < _index-1: 61 p = p.next 62 count += 1 63 p.next = p.next.next 64 self.length -= 1 65 66 def node_updata(self, _index, data): 67 """Replace the value of the element corresponding to _index with data""" 68 69 if _index < 1 or _index > self.length: 70 print('IndexError: out of index, fail to updata') 71 return 72 p = self.head.next 73 count = 1 74 while count < _index: 75 p = p.next 76 count += 1 77 p.data = data 78 79 def getItem(self, _index): 80 """Get the value of the element corresponding to _index""" 81 82 if _index < 1 or _index > self.length: 83 print('IndexError: out of index, fail to getitem') 84 return 85 p = self.head.next 86 count = 1 87 while count < _index: 88 p = p.next 89 count += 1 90 return p.data 91 92 def getIndex(self, data): 93 """Get the index of the element data""" 94 95 if self.isEmpty(): 96 print('the linklist is empyt, fail to getindex') 97 return 98 p = self.head.next 99 count = 1 100 while p and p.data != data: 101 p = p.next 102 count += 1 103 if count == self.length+1: 104 print('%s not found' % str(data)) 105 return 106 else: 107 return count 108 109 def traverse_linklist(self): 110 """Traversing the linklist""" 111 112 p = self.head.next 113 if p == None: 114 print('empty linklist') 115 while p: 116 print(p.data, end=' ') 117 p = p.next 118 119 def reverse_linklist(self): # reverse_linklist()是一个生成器函数，而不是普通函数 120 pre = None 121 _next = None 122 p = self.head.next 123 while p: 124 _next = p.next 125 p.next = pre 126 pre = p 127 p = _next 128 self.head.next = pre 129 130 p = self.head.next 131 while p: 132 yield p.data 133 p = p.next
双链表的实现（双链表在结点定义、初始化链表和插入删除上和单链表稍有不同）：
1 class Node: 2 """define the node of linklist""" 3 4 def __init__(self, data=None, prior=None, next=None): 5 self.data = data 6 self.prior_item = prior 7 self.next_item = next 8 9 10 def init_linklist(self, data): 11 """initial linklist""" 12 p = self.head 13 for i in data: 14 node = Node(i, prior=p) 15 p.next_item = node 16 p = p.next_item 17 self.length += 1 18 19 def insert(self, _index, data): 20 """Insert an element into the linklist""" 21 if _index < 1 or _index > self.length+1: 22 print('IndexError: out of index, fail to insert') 23 return 24 p = self.head 25 node = Node(data) 26 count = 0 27 while count < _index-1: 28 p = p.next_item 29 count += 1 30 node.next_item = p.next_item 31 p.next_item = node 32 node.prior_item = p 33 if node.next_item != None: 34 node.next_item.prior_item = node 35 self.length += 1 36 37 def delt(self, _index): 38 """Delete the value of the element corresponding to _index""" 39 if _index < 1 or _index > self.length: 40 print('IndexError: out of index, fail to delete') 41 return 42 p = self.head 43 count = 0 44 while count < _index-1: 45 p = p.next_item 46 count += 1 47 p.next_item = p.next_item.next_item 48 p.next_item.prior_item = p 49 self.length -= 1
单循环链表的实现（需要修改初始化和插入方法）：
1 def init_linklist(self, data): 2 """initial linklist""" 3 p = self.head 4 for i in data: 5 node = Node(i, next=self.head) 6 p.next_item = node 7 p = p.next_item 8 self.length += 1 9 10 def insert(self, _index, data): 11 """Insert an element into the linklist""" 12 if _index < 1 or _index > self.length+1: 13 print('IndexError: out of index, fail to insert') 14 return 15 p = self.head 16 node = Node(data) 17 count = 0 18 while count < _index-1: 19 p = p.next_item 20 count += 1 21 node.next_item = p.next_item 22 # If the inserted position is the end of the linklist 23 if node.next_item == None: 24 node.next_item = self.head 25 p.next_item = node 26 self.length += 1
双循环链表的实现（修改初始化和插入方法）：
1 def init_linklist(self, data): 2 """initial linklist""" 3 p = self.head 4 for i in data: 5 node = Node(i, prior=p, next=self.head) 6 p.next_item = node 7 p = p.next_item 8 self.head.prior_item = node 9 self.length += 1 10 11 def insert(self, _index, data): 12 """Insert an element into the linklist""" 13 if _index < 1 or _index > self.length+1: 14 print('IndexError: out of index, fail to insert') 15 return 16 p = self.head 17 node = Node(data) 18 count = 0 19 while count < _index-1: 20 p = p.next_item 21 count += 1 22 node.next_item = p.next_item 23 p.next_item = node 24 node.prior_item = p 25 # If the inserted position is the end of the linklist 26 if node.next_item == None: 27 node.next_item = self.head 28 self.head.prior_item = node 29 self.length += 1