链表的基本操作

"""
初始化链表
"""
import timeclass Node:def __init__(self,value):self.value = valueself.next = Noneclass SingleLinkList:def __init__(self):self.head = Nonedef is_empty(self):"""判断是否为空"""return self.head == Nonedef travel(self):"""遍历链表"""cur = self.headwhile cur is not None:print(cur.value,end=" ")cur = cur.nextdef append(self,item):"""在末尾添加节点"""node = Node(item)# 如果是空链表if self.is_empty():self.head = nodereturn# 当不为空的时候cur = self.headwhile cur.next:cur = cur.nextcur.next = node# node.next = Nonedef insert(self,index,item):"""插入中间节点"""if (self.head is None) and (self.head.next is None):returncur = self.headwhile cur is not None and index > 1:index = index - 1cur = cur.nextnode = Node(item)node.next = cur.nextcur.next = nodedef add(self,item):"""在头部添加节点"""node = Node(item)node.next = self.headself.head = nodedef length(self):"""获取链表的长度"""cur = self.headcount = 0while cur is not None:count += 1cur = cur.nextreturn countdef search(self,item):# 查看item在链表中是否存在cur = self.headwhile cur != None:if cur.value == item:return Trueelse:cur = cur.nextreturn Falsedef pop_last(self):"""弹出链表的最后一个元素"""if self.head is None:returncur = self.headif cur.next is None:self.head = Nonereturnwhile cur.next.next is not None:cur = cur.nextcur.next = Nonedef pop_head(self):"""把链表的第一个元素弹出"""if self.head is None:returnself.head = self.head.nextdef cycle(self):"""循环输出链表"""cur = self.headif cur.next == None:cur.next = self.headwhile cur.next != None:self.travel()time.sleep(3)if __name__ == '__main__':s = SingleLinkList()s.append(100)s.append(300)s.append(600)s.add(500)s.add(150)head = Node(30)head.next = Node(40)head.next.next = Node(50)s.pop_head()s.pop_last()s.cycle()s.travel()