1. 实现单向循环链表
class Node(): """定义结点""" def __init__(self,item): self.item=item self.next=None class SingleLoopLinkList(object): """单向循环链表""" def __init__(self,node=None): self.__head=node if node: # 如果把一个节点挂到单向循环链表的链子中，需要指向自身（构成一个循环） node.next=node def is_empty(self): """判断单向循环链表是否为空""" if self.__head is None: return True return False def length(self): """求单链表的长度""" count=1 cur=self.__head while cur.next is not self.__head: count+=1 cur=cur.next return count def travel(self): """单向循环链表的遍历""" cur=self.__head while cur.next is not self.__head: print(cur.item,end=" ") cur=cur.next print(cur.item,end=" ") print(" ") def add(self,item): """单向循环链表头部添加元素""" node=Node(item) cur=self.__head if cur is None: self.__head=node node.next=self.__head else: while cur.next is not self.__head: cur=cur.next node.next=self.__head self.__head=node cur.next=node def append(self,item): """单向循环链表尾部追加元素""" node=Node(item) cur=self.__head if cur is None: self.__head=node node.next=self.__head else: while cur.next is not self.__head: cur=cur.next cur.next=node node.next=self.__head def insert(self,pos,item): """单向循环链表指定位置插入元素""" count=0 node=Node(item) cur=self.__head if pos<=0: self.add(item) elif pos>=self.length(): self.append(item) else: while count<pos-1: cur=cur.next count+=1 node.next=cur.next cur.next=node def search(self,item): """判断单向循环链表是否存在某一个元素""" cur=self.__head while cur.next is not self.__head: if cur.item ==item: return True cur=cur.next if cur.item==item: return True return False def remove(self,item): """单向循环链表删除某一个元素""" if self.search(item): pre=None cur=self.__head while cur.next is not self.__head: if cur.item==item: if cur ==self.__head: pre=cur.next while cur.next is not self.__head: cur=cur.next cur.next=pre self.__head=pre else: pre.next=cur.next break else: pre=cur cur=cur.next if cur.item==item: pre.next=self.__head if __name__=="__main__": slll=SingleLoopLinkList() print(slll.is_empty()) slll.add(10000000) slll.append(1) slll.append(2) slll.append(3) slll.append(4) slll.add(0) print(slll.length()) slll.travel() slll.insert(0,1000) slll.insert(2,3000) slll.insert(20,2000) slll.travel() slll.remove(1000) slll.remove(2000) slll.travel()
运行结果：
2. 单向循环链表（版本二）
头插法，尾插法，查找，删除元素，一定要考虑特殊情况：比如链表是否为空，链表是否只有一个结点，链表的头结点，尾部结点等！！
class Node(): """定义结点""" def __init__(self,item): self.item=item self.next=None class SingleLoopLinkList(object): """单向循环链表""" def __init__(self,node=None): self.__head=node if node: # 如果把一个节点挂到单向循环链表的链子中，需要指向自身（构成一个循环） node.next=node def is_empty(self): """判断单向循环链表是否为空""" if self.__head is None: return True return False def length(self): """求单向循环链表的长度""" count=1 cur=self.__head if self.__head is None: # 单项循环链表为空 return 0 else: while cur.next is not self.__head: count+=1 cur=cur.next return count def travel(self): """单向循环链表的遍历""" cur=self.__head if self.is_empty(): # 是一个空链表 return while cur.next is not self.__head: print(cur.item,end=" ") cur=cur.next print(cur.item,end=" ") print(" ") def add(self,item): """单向循环链表头部添加元素""" node=Node(item) cur=self.__head if cur is None: self.__head=node node.next=self.__head else: while cur.next is not self.__head: cur=cur.next node.next=self.__head self.__head=node cur.next=node def append(self,item): """单向循环链表尾部追加元素""" node=Node(item) cur=self.__head if cur is None: self.__head=node node.next=self.__head else: while cur.next is not self.__head: cur=cur.next cur.next=node node.next=self.__head def insert(self,pos,item): """单向循环链表指定位置插入元素""" count=0 node=Node(item) cur=self.__head if pos<=0: self.add(item) elif pos>=self.length(): self.append(item) else: while count<pos-1: cur=cur.next count+=1 node.next=cur.next cur.next=node def search(self,item): """判断单向循环链表是否存在某一个元素""" cur=self.__head if self.is_empty(): # 空链表 return while cur.next is not self.__head: if cur.item ==item: return True cur=cur.next if cur.item==item: return True return False def remove(self,item): """单向循环链表删除某一个元素""" if self.search(item): pre=None cur=self.__head while cur.next is not self.__head: if cur.item==item: if cur ==self.__head: pre=cur.next while cur.next is not self.__head: cur=cur.next cur.next=pre self.__head=pre else: pre.next=cur.next break else: pre=cur cur=cur.next if cur.item==item: if self.length()==1: # 单项循环链表只有一个元素，且是需要删除的元素 self.__head=None else: pre.next=self.__head if __name__=="__main__": slll=SingleLoopLinkList() print(slll.is_empty()) slll.add(10000000) slll.remove(10000000) print(slll.length()) slll.append(1) slll.append(2) slll.append(3) slll.append(4) slll.add(0) print(slll.length()) slll.travel() slll.insert(0,1000) slll.insert(2,3000) slll.insert(20,2000) slll.travel() slll.remove(1000) slll.remove(2000) slll.travel()