python语言下的链表使用

SingleLinkList ()  创建一个空链表

is_empty（）判断链表是否为空

length（）链表长度

travel（）遍历整个链表

add（item）链表头部添加元素

append（item）链表尾部添加元素

insert（pos，item）在指定位置添加元素

remove（item）删除节点

search（item）查找节点是否存在

# 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):
        """链表是否为空"""
        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
        # countj=记录数量
        count = 0
        while cur != None:
            count += 1
            cur = cur.next
        return count

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

    def add(self, item):
        """链表头部添加元素"""
        node = Node(item)
        if self.is_empty():
            self.__head = node
        else:
            cur = self.__head
            while cur.next !=None:
                cur = cur.next
            cur.next = node


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

    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):
                count += 1
                pre=pre.next
            #当循环退出后，pre指向pos-1位置
            node = Node(item)
            node.next = pre.next
            pre.next = node


    def remove(self,item):
        """删除节点"""
        cur = self.__head
        pre = None
        while cur != None:
            if cur.elem == item:
                #先判断此节点是否为头节点
                #头节点
               if cur == self.__head:
                   self.__head = cur.next
               else:
                   pre.next = cur.next
               break
            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 = cur.next
            return  False


if __name__=="__main__":
    ll=SingleLinkList()
    print(ll.is_empty())
    print(ll.length())

    ll.append(1)
    print(ll.is_empty())
    print(ll.length())

    ll.append(2)
    ll.add(8)
    ll.travel()
    ll.append(3)
    ll.append(4)
    ll.append(5)
    ll.append(6)
    ll.append(7)
    ll.insert(-1,9)#9 8 1 234567
    ll.travel()
    ll.insert(3,99)#9 8 1 99 234567
    ll.travel()
    ll.remove(9)

    用法实例