如何修复链表位置中间的添加值

Question

I'm creating a single linked list insert beginning, end, and middle of the linked list. After running code inserting the middle is not working in the linked list changing location value randomly and after running it's not getting. Can anyone suggest what is wrong with the code?

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


class SLinkedList:
    def __init__(self):
        self.head = None
        self.tail = None

    def __iter__(self):
        node = self.head
        while node:
            yield node
            node = node.next

    def insertsll(self, value, location):
        new_node = Node(value)
        if self.head is None:
            self.head = new_node
            self.tail = new_node
        else:
            if location == 0:
                new_node.next = self.head
                self.head = new_node
            elif location == 1:
                new_node.next = None
                self.tail.next = new_node
                self.tail = new_node
            else:
                temp_node = self.head
                index = 0
                while index < location - 1:
                    temp_node = temp_node.next
                    index += 1
                    next_node = temp_node.next
                    temp_node.next = new_node
                    new_node.next = next_node
                    # if temp_node == self.tail:
                    #     self.tail = new_node




sll = SLinkedList()
sll.insertsll(1, 1)
sll.insertsll(2, 1)
sll.insertsll(3, 1)
sll.insertsll(4, 1)
sll.insertsll(0, 0)
sll.insertsll(60, 3)---> run this random changing location not working in correct location
sll.insertsll(50, 4)---> run this random changing location  not working in correct location

print([node.value for node in sll])

output: [0, 1, 50, 2, 3, 4]

Process finished with exit code 0

Answer 1

I think the iteration in the while loop was a little bit too complicated. I think with this code it is more understandable what the insert does. Also, I don't know why you had the location === 1 check. It seems to be not necessary.

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


class SLinkedList:
    def __init__(self):
        self.head = None
        self.tail = None

    def __iter__(self):
        node = self.head
        while node:
            yield node
            node = node.next

    def insertsll(self, value, location):
        new_node = Node(value)
        if self.head is None:
            self.head = new_node
            self.tail = new_node
        else:
            if location == 0:
                new_node.next = self.head
                self.head = new_node
            else:
                temp_node = self.head
                index = 0
                
                # Iterate to insert location
                while index < location - 1:
                    index += 1
                    temp_node = temp_node.next

                # Insert new node
                new_node.next = temp_node.next
                temp_node.next = new_node
                
                # Check if new node is tail
                if new_node.next is None:
                    self.tail = new_node



sll = SLinkedList()
sll.insertsll(1, 1)
sll.insertsll(2, 1)
sll.insertsll(3, 1)
sll.insertsll(4, 1)
sll.insertsll(0, 0)
sll.insertsll(60, 3)
sll.insertsll(50, 4)

print([node.value for node in sll])

Output:

[0, 1, 4, 60, 50, 3, 2]

PS: Such a structure really benefits from a length attribute. This can be used to check if an insert operation is even allowed. Probably, you should consider adding it.