1 # -*- coding: utf-8 -*-
2 # @author: Tele
3 # @Time : 2019/04/22 下午 3:17
4 # 单向链表的实现
5 # 每个节点包含两部分,数据区和指向下个节点的链接
6 # 单向列表:每个节点包含两部分:数据区与链接区(指向下一个节点),最后一个元素的链接区为None
7 # 单向列表只要找到头节点,就可以访问全部节点
8 class SingleNode:
9 def __init__(self, data, next=None):
10 self.data = data
11 # next指向下一个节点而不是数据
12 self.next = next
13
14
15 # 使用链表时只需要传入待存储的数据而不是节点
16 class SingleLinkedList:
17 def __init__(self, data=None):
18 node = SingleNode(data)
19 self.__head = node if node.data else None
20
21 def is_empty(self):
22 return self.__head == None
23
24 def length(self):
25 count = 0
26 cur = self.__head
27 while cur:
28 count += 1
29 cur = cur.next
30 return count
31
32 # 头部添加元素
33 def add(self, data):
34 node = SingleNode(data)
35 node.next = self.__head
36 self.__head = node
37
38 # 尾部添加元素
39 def append(self, data):
40 node = SingleNode(data)
41 if self.is_empty():
42 self.__head = node
43 else:
44 cur = self.__head
45 # 最后一个节点的next为None
46 while cur.next:
47 cur = cur.next
48 cur.next = node
49
50 # 指定位置插入
51 def insert(self, pos, data):
52 node = SingleNode(data)
53 cur = self.__head
54 count = 0
55 if self.length() >= pos >= 0:
56 while cur:
57 if count + 1 == pos:
58 node.next = cur.next
59 cur.next = node
60 break
61 # pos为0
62 elif count == pos:
63 self.add(data)
64 break
65 count += 1
66 cur = cur.next
67 elif pos < 0:
68 self.add(data)
69 else:
70 self.append(data)
71 # 如果列表中插入时没有元素
72 if not self.__head:
73 self.append(data)
74
75 # 遍历
76 def travel(self):
77 cur = self.__head
78 while cur:
79 print(cur.data)
80 cur = cur.next
81
82 # 移除出现的第一个元素
83 def remove(self, data):
84 if self.is_empty():
85 return
86 node = self.__find(data)
87 cur = self.__head
88 while cur:
89 # 如果要移除的元素是头节点
90 if cur.data == node.data:
91 self.__head = cur.next
92 break
93 elif cur.next.data == node.data:
94 cur.next = node.next
95 break
96 cur = cur.next
97
98 # 私有方法,用于查找节点
99 def __find(self, data):
100 cur = self.__head
101 node = SingleNode(data)
102 while cur:
103 if cur.data == data:
104 node.next = cur.next
105 break
106 cur = cur.next
107 return node
108
109 # 查找,找不到返回-1,找到则返回索引
110 def search(self, data):
111 index = -1
112 cur = self.__head
113 count = 0
114 while cur:
115 if cur.data == data:
116 index = count
117 break
118 count += 1
119 cur = cur.next
120 return index
121
122
123 def main():
124 ssl = SingleLinkedList()
125 print(ssl.is_empty())
126 print(ssl.length())
127 # ssl.append(1)
128 # ssl.append(100)
129 # ssl.append(2)
130 # ssl.append(200)
131 # ssl.append(3)
132 # ssl.append(4)
133 print(ssl.is_empty())
134 print(ssl.length())
135
136 # 遍历
137 print("*" * 50)
138 # ssl.travel()
139
140 ssl.add(100)
141 # ssl.travel()
142 # 为负数时作为头节点
143 ssl.insert(-1, "sss")
144 ssl.travel()
145 print("*" * 50)
146 print(ssl.search("sss")) # 0
147 print("*" * 50)
148 ssl.remove(100)
149 ssl.travel()
150
151
152 if __name__ == '__main__':
153 main()