普通单链表和单向循环链表的不同之处在于单向循环链表成环，在这种情况下链表指针移动到尾部的判定条件要发生改变，增删改查也要发生改变，但还是以本博客的"python实现单链表"中的代码为基础来实现的。
# 单向循环链表 class Node(object): """节点类""" def __init__(self,elem): self.elem = elem self.next = None class SingLinkList(object): """单向循环链表类""" def __init__(self,node=None): self.__head = node if node: node.next = node def is_empty(self): """判断链表是否为空""" return self.__head == None def length(self): """返回链表的长度""" #如果是空链表则返回0 if self.is_empty(): return 0 #cur游标移动，从而实现遍历元素的功能 cur = self.__head #count用来计数 count = 1 while cur.next != self.__head: count += 1 #让cur游标可以向下移动 cur = cur.next return count def travel(self): """遍历整个链表""" if self.is_empty(): return #建立游标等于起始节点 cur = self.__head while cur.next != self.__head: print(cur.elem,end=" ") cur = cur.next print(cur.elem,end="\n") def add(self,item): """链表头部添加元素""" node = Node(item) if self.is_empty(): self.__head = node node.next = node return else: cur = self.__head while cur.next != self.__head: cur = cur.next # self.__head记录了它指向的下一个元素的地址，就是把__head后面元素的值给了新节点 node.next = self.__head self.__head = node cur.next = self.__head def append(self,item): """链表尾部添加元素""" node = Node(item) #建立节点 #链表是否为空链表 if self.is_empty(): self.__head = node node.next = node else: cur = self.__head #设置指向头结点的游标 while cur.next != self.__head: cur = cur.next #添加节点到尾部 node.next = self.__head cur.next = node def insert(self,pos,item): """在指定位置添加元素""" #指向不是头部元素，self.__head的地址 # 为下一个元素，所以pre为下一个元素 if pos <= 0: #认为是头插法 self.add(item) elif pos > (self.length()-1): self.append(item) else: pre = self.__head count = 0 while count < (pos-1): count+=1 pre = pre.next node = Node(item) node.next = pre.next pre.next = node def remove(self,item): """删除元素""" if self.is_empty(): return cur = self.__head pre = None while cur.next != self.__head: if cur.elem == item: #判断此节点是否为头节点 #是头节点 if cur == self.__head: #设置尾节点并找到尾部 rear = self.__head while rear.next != self.__head: rear = rear.next #到这里是rear指向尾部 self.__head = cur.next #删除第一个元素 rear.next = self.__head #尾部指向第二个元素 # self.__head = cur.next else: #中间节点 pre.next = cur.next return else: #cur,pre游标都向下移动 pre = cur cur = cur.next #删除尾节点 if cur.elem == item: if cur == self.__head: self.__head = None else: pre.next = cur.next def search(self,item): """查找结点是否存在""" #如果是一个空链表 if self.is_empty(): return False cur = self.__head while cur.next != self.__head: if cur.elem == item: return True else: cur = cur.next return False if __name__ == '__main__': ll = SingLinkList() print(ll.is_empty()) print(ll.length()) ll.append(1) print(ll.is_empty()) print(ll.length()) ll.append(2) ll.append(3) ll.append(4) ll.append(5) ll.travel() ll.insert(-1,20) ll.travel() ll.insert(2,30) ll.travel() ll.insert(10,200) ll.travel() ll.remove(20) ll.travel() ll.remove(200) ll.travel() 文章来源: https://blog.csdn.net/qq_39112101/article/details/91490668