python实现单向链表

废话不说，直接上代码

#-*-coding=utf-8-*-
class Node(object):
    """节点"""
    def __init__(self,elem):
        self.elem=elem
        self.next=None

class SingleLinkList(object):
    """单链表"""
    def __init__(self,node=None):
        self.__head = node

    def is_empty(self):
        """判断是否为空"""
        return self.__head==None

    def length(self):
        """链表长度"""
        #cur游标，用来移动遍历节点
        cur = self.__head
        #count记录数量
        count=0
        while cur!=None:
            cur=cur.next
            count+=1
        return count

    def travel(self):
        """遍历整个链表"""
        cur=self.__head
        while cur!=None:
            print(cur.elem)
            cur=cur.next

    def add(self,item):
        """链表头部添加元素"""
        node=Node(item)
        node.next=self.__head
        self.__head=node

    def append(self,item):
        """链表尾部添加元素"""
        if self.is_empty():
            self.__head=Node(item)
        else:
            cur=self.__head
            while cur.next!=None:
                cur=cur.next
            cur.next=Node(item)

    def insert(self,pos,item):
        """指定位置添加元素"""
        if pos<=0:
            self.add(item)
        elif pos>self.length()-1:
            self.append(item)
        else:
            pre=self.__head
            count=0
            while count<pos-1:
                pre=pre.next
                count+=1
            Node(item).next=pre.next
            pre.next=Node(item)

    def remove(self,item):
        """删除节点"""
        cur=self.__head
        pre=None
        while cur!=None:
            if cur.elem==item:
                if cur==self.__head:
                    self.__head=cur.next
                pre.next=cur.next
            else:
                pre=cur
                cur=cur.next



    def search(self,item):
        """查找节点是否存在"""
        cur=self.__head
        while cur!=None:
            if cur.elem==item:
                return True
            else:
                cur.next
        return False


if __name__=="__main__":
    ll=SingleLinkList()
    print(ll.is_empty())
    print(ll.length())
    ll.append(1)
    ll.append(2)
    ll.append(3)
    ll.append(4)
    ll.append(5)
    ll.append(6)
    ll.append(7)
    print(ll.is_empty())
    print(ll.length())
    ll.travel()