連結串列的定義:
連結串列(linked list)是由一組被稱為結點的資料元素組成的資料結構,每個結點都包含結點本身的資訊和指向下一個結點的地址。由於每個結點都包含了可以連結起來的地址資訊,所以用一個變數就能夠訪問整個結點序列。也就是說,結點包含兩部分資訊:一部分用於儲存資料元素的值,稱為資訊域;另一部分用於儲存下一個資料元素地址的指標,稱為指標域。連結串列中的第一個結點的地址儲存在一個單獨的結點中,稱為頭結點或首結點。連結串列中的最後一個結點沒有後繼元素,其指標域為空。
如下圖所示:
單連結串列的結構:
單連結串列的插入和刪除示意圖:
python實現程式碼:
#!/usr/bin/python # -*- coding: utf-8 -*- class Node(object): def __init__(self,val,p=0): self.data = val self.next = p class LinkList(object): def __init__(self): self.head = 0 def __getitem__(self, key): if self.is_empty(): print 'linklist is empty.' return elif key <0 or key > self.getlength(): print 'the given key is error' return else: return self.getitem(key) def __setitem__(self, key, value): if self.is_empty(): print 'linklist is empty.' return elif key <0 or key > self.getlength(): print 'the given key is error' return else: self.delete(key) return self.insert(key) def initlist(self,data): self.head = Node(data[0]) p = self.head for i in data[1:]: node = Node(i) p.next = node p = p.next def getlength(self): p = self.head length = 0 while p!=0: length+=1 p = p.next return length def is_empty(self): if self.getlength() ==0: return True else: return False def clear(self): self.head = 0 def append(self,item): q = Node(item) if self.head ==0: self.head = q else: p = self.head while p.next!=0: p = p.next p.next = q def getitem(self,index): if self.is_empty(): print 'Linklist is empty.' return j = 0 p = self.head while p.next!=0 and j <index: p = p.next j+=1 if j ==index: return p.data else: print 'target is not exist!' def insert(self,index,item): if self.is_empty() or index<0 or index >self.getlength(): print 'Linklist is empty.' return if index ==0: q = Node(item,self.head) self.head = q p = self.head post = self.head j = 0 while p.next!=0 and j<index: post = p p = p.next j+=1 if index ==j: q = Node(item,p) post.next = q q.next = p def delete(self,index): if self.is_empty() or index<0 or index >self.getlength(): print 'Linklist is empty.' return if index ==0: q = Node(item,self.head) self.head = q p = self.head post = self.head j = 0 while p.next!=0 and j<index: post = p p = p.next j+=1 if index ==j: post.next = p.next def index(self,value): if self.is_empty(): print 'Linklist is empty.' return p = self.head i = 0 while p.next!=0 and not p.data ==value: p = p.next i+=1 if p.data == value: return i else: return -1 l = LinkList() l.initlist([1,2,3,4,5]) print l.getitem(4) l.append(6) print l.getitem(5) l.insert(4,40) print l.getitem(3) print l.getitem(4) print l.getitem(5) l.delete(5) print l.getitem(5) l.index(5)
結果:
5
6
4
40
5
6