单向链表的python实现

  1 class Node():
  2     def __init__(self,item):
  3         #初始化这个节点，值和下一个指向
  4         self.item = item
  5         self.next = None
  6 
  7 class SingleLinklist():
  8     def __init__(self):
  9         #初始化这个单链表的头指针为空
 10         self._head = None
 11 
 12     def length(self):
 13         #获取这个链表的长度
 14         count = 0
 15         cur = self._head
 16         while cur != None:
 17             count+=1
 18             cur = cur.next
 19         return count
 20 
 21     def is_empty(self):
 22         """判断是否为空"""
 23         return self._head == None
 24 
 25     def add(self,item):
 26         """在头部添加元素"""
 27         node = Node(item)
 28         node.next = self._head
 29         self._head = node
 30 
 31     def append(self,item):
 32         """在尾部添加元素"""
 33         cur = self._head
 34         node = Node(item)
 35         while cur != None:
 36             cur = cur.next
 37         cur.next = node
 38 
 39     def insert(self,pos,item):
 40         """在选定的位置添加元素"""
 41         cur = self._head
 42         node = Node(item)
 43         count = 0
 44         if pos <= 0:
 45             self.add(item)
 46         elif pos > (self.length()-1):
 47             self.append(item)
 48         else:
 49             while count < (pos -1):
 50                 count+=1
 51                 cur = cur.next
 52             node.next = cur.next
 53             cur.next = node
 54 
 55 
 56     def travel(self):
 57         """遍历整个链表"""
 58         cur = self._head
 59         while cur != None:
 60             print(cur.item,end=" ")
 61             cur = cur.next
 62         print(" ")
 63 
 64     def remove(self,item):
 65         """删除链表"""
 66         cur = self._head
 67         pre =None
 68         while cur != None:
 69             if cur.item == item:
 70                 if not pre:
 71                     self._head = cur.next
 72                     break
 73                 else:
 74                     pre.next = cur.next
 75             else:
 76                 pre = cur #
 77                 cur = cur.next
 78 
 79     def search(self,item):
 80         """查找某个节点"""
 81         cur = self._head
 82         while cur != None:
 83             if cur.item == item:
 84                 print("找到这个元素了")
 85                 return True
 86             cur = cur.next
 87         print("抱歉没有这个元素")
 88         return False
 89 
 90 singlistdemo = SingleLinklist()
 91 singlistdemo.add(1)
 92 singlistdemo.add(2)
 93 singlistdemo.add(65)
 94 singlistdemo.insert(2,77)
 95 singlistdemo.insert(1,66)
 96 singlistdemo.insert(0,66)
 97 
 98 
 99 print(singlistdemo.length())
100 singlistdemo.travel()
101 singlistdemo.remove(1)
102 singlistdemo.travel()
103 singlistdemo.search(65)