在链表的尾部插入一个元素

Question

Have to write the method def insert(self,newElement) which inserts an element at the end of a linked list. If the element already exists in the list then it prints "Value already exists" and does not insert the element. I have tried this code :

class Node:
    def __init__(self,value,next=None):
        self.value=value
        self.next=next

class MyList:
    def __init__(self,a):
        self.head=None
        tail=None
        for i in a:
            n=Node(i,None)
            if self.head is None:
                self.head=n
                tail=n
            else:
                tail.next=n
                tail=n
  
    def showList(self):
        n=self.head
        if n==None:
            print("Empty list")
        while n!=None:
            print(n.value)
            n=n.next
    
    def isEmpty(self):
        n=self.head
        if n is None:
            print("True")
        else:
            print("False")

    def clear(self):
        while(self.head!=None):
            temp=self.head
            self.head=self.head.next
            temp=None

    def insert(self, newElement):
        n = self.head
        newNode = Node(newElement)
        while(n!=None):
            if(n.value==newNode.value):
                print("Value already exists")
            n=n.next
    
        temp = self.head
        while(temp.next != None):
            temp = temp.next
        temp.next = newNode
        print(self.showList())

class tester:
list1 = [1, 2, 3, 4, 5]
linklist = MyList(list1)
linklist.showList()
linklist.insert(5)
 

The problem is the method insert(self,newElement) is able to check if the new element already exists in the list but it is still inserting the element. The method should check if the new element already exists in list or not. If it exist then, the method should not insert the new element and if it doesn't exist then it should insert the new element. The code I provided above can check if the new element already exist in the list but it is unable to stop inserting the new element.

Answer 1

Have to write the method def insert(self,newElement) which inserts an element at the end of a linked list. If the element already exists in the list then it prints "Value already exists" and does not insert the element. I have tried this code :

class Node:
    def __init__(self,value,next=None):
        self.value=value
        self.next=next

class MyList:
    def __init__(self,a):
        self.head=None
        tail=None
        for i in a:
            n=Node(i,None)
            if self.head is None:
                self.head=n
                tail=n
            else:
                tail.next=n
                tail=n
  
    def showList(self):
        n=self.head
        if n==None:
            print("Empty list")
        while n!=None:
            print(n.value)
            n=n.next
    
    def isEmpty(self):
        n=self.head
        if n is None:
            print("True")
        else:
            print("False")

    def clear(self):
        while(self.head!=None):
            temp=self.head
            self.head=self.head.next
            temp=None

    def insert(self, newElement):
        n = self.head
        newNode = Node(newElement)
        while(n!=None):
            if(n.value==newNode.value):
                print("Value already exists")
            n=n.next
    
        temp = self.head
        while(temp.next != None):
            temp = temp.next
        temp.next = newNode
        print(self.showList())

class tester:
list1 = [1, 2, 3, 4, 5]
linklist = MyList(list1)
linklist.showList()
linklist.insert(5)
 

The problem is the method insert(self,newElement) is able to check if the new element already exists in the list but it is still inserting the element. The method should check if the new element already exists in list or not. If it exist then, the method should not insert the new element and if it doesn't exist then it should insert the new element. The code I provided above can check if the new element already exist in the list but it is unable to stop inserting the new element.