LinkedList python 删除问题 function

Question

I'm writing a simple linked list code in Python, could you tell me whats wrong with the deleteT function. it's not doing its job

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


class SinglyLL():
    def __init__(self,value):
        self.head=SinglyLLNode(value)

    def getTail(self):
        n=self.head
        while n.next != None:
            n = n.next
        return n

    def display(self):

        n = self.head
        a=[]
        while n != None:
            a.append(n.value)
            n = n.next

        print(*a,sep=" -> ")

    def insertT(self,value):
        n = self.getTail()
        n.next=SinglyLLNode(value)

    def deleteT(self):
        n=self.head

        if n is None:
            print("Cant Delete Empty List")
            return

        elif n.next is None:
            del n
            return
        else:
            prev = n
            while n.next is not None:
                prev = n
                n = n.next

            prev.next = n



N = SinglyLL(100)
N.insertT(123)
N.insertT(1234)
N.display()
N.deleteT()
N.insertT(12345)
N.display()

the output is:

100 -> 123 -> 1234

100 -> 123 -> 1234 -> 12345

but should be 100 -> 123 -> 12345

PS: Sorry for big code kindly just see the deleteT() function others are working well

Answer 1

This deleteT function will remove the last element of the linked list, ensuring the the new last element points to None :

def deleteT(self):
        n=self.head

        if n is None:
            print("Cant Delete Empty List")
            return

        elif n.next is None:
            del n
            return
        else:
            while n.next.next is not None:
                n = n.next
            del n.next.next
            n.next = None