[数据结构与算法]单链表的练习

class Node(object):
    def __init__(self,item):
        self.item=item
        self.next=None
class SigleLinkList(object):
    def __init__(self):
        self.__head=None
    def is_empty(self):
        return self.__head==None
    def length(self):
        cur=self.__head
        count=0
        while cur!=None:
            count+=1
            cur=cur.next
        return count
    def trave(self):
        cur=self.__head
        while cur !=None:
            print(cur.item,end="")
            cur = cur.next
    def add(self,item):
        node = Node(item)
        node.next = self.__head
        self.__head = node

    def append(self,item):
        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):
        if pos<0:
            self.add(item)
        elif pos>(self.length()-1):
            self.append(item)
        node=Node(item)
        pre=self.__head
        count=0
        while count<(pos-1):
            count+=1
            pre=pre.next
        node.next=pre.next
        pre.next=node
    def search(self,item):
        cur=self.__head
        while cur != None:
            if cur.elem==item:
                return True
            else:
                cur = cur.next
    def remove(self,item):
        cur = self.__head
        pre=None
        while cur!= None:
            if cur.item==item:
                if cur==self.__head:
                    self.__head=cur.next
                else:
                    pre.next=cur.next
                break
            else:
                pre=cur
                cur=cur.next



if __name__=="__main__":
    ll=SigleLinkList()
    print(ll.is_empty())
    print(ll.length())
    print("-"*20)
    ll.append(1)
    print(ll.is_empty())
    print(ll.length())
    print("-" * 20)
    ll.append(2)
    ll.append(3)
    ll.append(4)
    ll.append(5)
    ll.append(6)
    ll.append(7)
    ll.add(8)
    ll.trave()

    print(" ")
    print("-" * 20)
    ll.insert(5, 100)
    ll.trave()
    print(" ")
    print("-" * 20)
    ll.remove(100)
    ll.trave()

True
0
--------------------
False
1
--------------------
81234567?
--------------------
81234100567?
--------------------
81234567