鏈表由一系列不必在內存中相連的結構構成，這些對象按線性順序排序。每個結構含有表元素和指向后繼元素的指針。最后一個單元的指針指向NULL。為了方便鏈表的刪除與插入操作，可以為鏈表添加一個表頭。
刪除操作可以通過修改一個指針來實現。
插入操作需要執行兩次指針調整。
1. 單向鏈表的實現
1.1 Node實現
每個Node分為兩部分。一部分含有鏈表的元素，可以稱為數據域；另一部分為一指針，指向下一個Node。
class Node(): __slots__=['_item','_next'] #限定Node實例的屬性 def __init__(self,item): self._item=item self._next=None #Node的指針部分默認指向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
1.2 SinglelinkedList的實現
class SingleLinkedList(): def __init__(self): self._head=None #初始化鏈表為空表 self._size=0
1.3 檢測鏈表是否為空
def isEmpty(self): return self._head==None
1.4 add在鏈表前端添加元素
def add(self,item): temp=Node(item) temp.setNext(self._head) self._head=temp
1.5 append在鏈表尾部添加元素
def append(self,item): temp=Node(item) if self.isEmpty(): self._head=temp #若為空表，將添加的元素設為第一個元素 else: current=self._head while current.getNext()!=None: current=current.getNext() #遍歷鏈表 current.setNext(temp) #此時current為鏈表最后的元素
1.6 search檢索元素是否在鏈表中
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
1.7 index索引元素在鏈表中的位置
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
1.8 remove刪除鏈表中的某項元素
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()
1.9 insert鏈表中插入元素
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)
全部代碼
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 #初始化為空鏈表 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 #若為空表，將添加的元素設為第一個元素 else: current=self._head while current.getNext()!=None: current=current.getNext() #遍歷鏈表 current.setNext(temp) #此時current為鏈表最后的元素 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()
