链表由一系列不必在内存中相连的结构构成，这些对象按线性顺序排序。每个结构含有表元素和指向后继元素的指针。最后一个单元的指针指向NULL。为了方便链表的删除与插入操作，可以为链表添加一个表头。
删除操作可以通过修改一个指针来实现。
插入操作需要执行两次指针调整。
1. 单向链表的实现
1.1 Node实现
每个Node分为两部分。一部分含有链表的元素，可以称为数据域；另一部分为一指针，指向下一个Node。
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class
Node():
__slots__=[‘_item‘,‘_next‘] #限定Node实例的属性
def
__init__(self,item):
self._item=item
self._next=None
#Node的指针部分默认指向None
def
getItem(self):
return
self._item
def
getNext(self):
return
self._next
def
setItem(self,newitem):
self._item=newitem
def
setNext(self,newnext):
self._next=newnext
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1.2 SinglelinkedList的实现
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class
SingleLinkedList():
def
__init__(self):
self._head=None
#初始化链表为空表
self._size=0
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1.3 检测链表是否为空
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def isEmpty(self):
return
self._head==None |
1.4 add在链表前端添加元素
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def add(self,item):
temp=Node(item)
temp.setNext(self._head)
self._head=temp
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1.5 append在链表尾部添加元素
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def append(self,item):
temp=Node(item)
if
self.isEmpty():
self._head=temp #若为空表，将添加的元素设为第一个元素
else:
current=self._head
while
current.getNext()!=None:
current=current.getNext() #遍历链表
current.setNext(temp) #此时current为链表最后的元素
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1.6 search检索元素是否在链表中
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def search(self,item):
current=self._head
founditem=False
while
current!=None
and not founditem:
if
current.getItem()==item:
founditem=True
else:
current=current.getNext()
return
founditem
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1.7 index索引元素在链表中的位置
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def index(self,item):
current=self._head
count=0
found=None
while
current!=None
and not found:
count+=1
if
current.getItem()==item:
found=True
else:
current=current.getNext()
if
found:
return
count
else:
raise
ValueError,‘%s is not in linkedlist‘%item
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1.8 remove删除链表中的某项元素
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def remove(self,item):
current=self._head
pre=None
while
current!=None:
if
current.getItem()==item:
if
not pre:
self._head=current.getNext()
else:
pre.setNext(current.getNext())
break
else:
pre=current
current=current.getNext()
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1.9 insert链表中插入元素
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def insert(self,pos,item):
if
pos<=1:
self.add(item)
elif
pos>self.size():
self.append(item)
else:
temp=Node(item)
count=1
pre=None
current=self._head
while
count<pos:
count+=1
pre=current
current=current.getNext()
pre.setNext(temp)
temp.setNext(current)
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全部代码
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class
Node():
__slots__=[‘_item‘,‘_next‘]
def
__init__(self,item):
self._item=item
self._next=None
def
getItem(self):
return
self._item
def
getNext(self):
return
self._next
def
setItem(self,newitem):
self._item=newitem
def
setNext(self,newnext):
self._next=newnext
class
SingleLinkedList():
def
__init__(self):
self._head=None
#初始化为空链表
def
isEmpty(self):
return
self._head==None
def
size(self):
current=self._head
count=0
while
current!=None:
count+=1
current=current.getNext()
return
count
def
travel(self):
current=self._head
while
current!=None:
print
current.getItem()
current=current.getNext()
def
add(self,item):
temp=Node(item)
temp.setNext(self._head)
self._head=temp
def
append(self,item):
temp=Node(item)
if
self.isEmpty():
self._head=temp #若为空表，将添加的元素设为第一个元素
else:
current=self._head
while
current.getNext()!=None:
current=current.getNext() #遍历链表
current.setNext(temp) #此时current为链表最后的元素
def
search(self,item):
current=self._head
founditem=False
while
current!=None
and not founditem:
if
current.getItem()==item:
founditem=True
else:
current=current.getNext()
return
founditem
def
index(self,item):
current=self._head
count=0
found=None
while
current!=None
and not found:
count+=1
if
current.getItem()==item:
found=True
else:
current=current.getNext()
if
found:
return
count
else:
raise
ValueError,‘%s is not in linkedlist‘%item
def
remove(self,item):
current=self._head
pre=None
while
current!=None:
if
current.getItem()==item:
if
not pre:
self._head=current.getNext()
else:
pre.setNext(current.getNext())
break
else:
pre=current
current=current.getNext()
def
insert(self,pos,item):
if
pos<=1:
self.add(item)
elif
pos>self.size():
self.append(item)
else:
temp=Node(item)
count=1
pre=None
current=self._head
while
count<pos:
count+=1
pre=current
current=current.getNext()
pre.setNext(temp)
temp.setNext(current)
if __name__==‘__main__‘:
a=SingleLinkedList()
for
i in
range(1,10):
a.append(i)
print
a.size()
a.travel()
print
a.search(6)
print
a.index(5)
a.remove(4)
a.travel()
a.insert(4,100)
a.travel()
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