Creating a Singly Linked List from Scratch in DSA Python - Code Step by Step

Practice - 5 Tasks

1fill in blank

easy

Complete the code to define a Node class with a constructor that initializes the data and next pointer.

DSA Python

class Node:
    def __init__(self, data):
        self.data = data
        self.[1] = None

Drag options to blanks, or click blank then click option'

Aprev

Bnext

Chead

Dvalue

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'prev' which is for doubly linked lists.

Using 'head' which is a pointer for the list, not the node.

Using 'value' which is not a standard pointer name.

The next attribute points to the next node in the list. It should be initialized to None when a new node is created.

2fill in blank

medium

Complete the code to initialize the head of the linked list to None in the LinkedList class constructor.

DSA Python

class LinkedList:
    def __init__(self):
        self.[1] = None

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Adata

Btail

Chead

Dnext

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'tail' which points to the end, not the start.

Using 'next' which belongs to nodes, not the list.

Using 'data' which is node content, not a pointer.

The head attribute points to the first node in the linked list. It should start as None when the list is empty.

3fill in blank

hard

Fix the error in the append method to correctly add a new node at the end of the linked list.

DSA Python

def append(self, data):
    new_node = Node(data)
    if self.head is None:
        self.head = new_node
    else:
        last = self.head
        while last.[1] is not None:
            last = last.next
        last.next = new_node

Drag options to blanks, or click blank then click option'

Anext

Bprev

Chead

Ddata

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'prev' which is not defined in singly linked lists.

Using 'head' which is the start of the list, not the next node.

Using 'data' which is the node's content, not a pointer.

The loop should check the next pointer to find the last node. Using next correctly traverses the list.

4fill in blank

hard

Fill both blanks to create a method that prints all node data in the linked list.

DSA Python

def print_list(self):
    current = self.head
    while current is not None:
        print(current.[1])
        current = current.[2]

Drag options to blanks, or click blank then click option'

Adata

Bnext

Chead

Dprev

Attempts:

3 left

💡 Hint

Common Mistakes

Trying to print 'next' instead of 'data'.

Using 'prev' which does not exist in singly linked lists.

Using 'head' which is the start pointer, not a node attribute.

To print the data, access the data attribute of the current node. To move forward, update current to current.next.

5fill in blank

hard

Fill all three blanks to create a method that counts the number of nodes in the linked list.

DSA Python

def length(self):
    count = 0
    current = self.[1]
    while current is not None:
        count [2]= 1
        current = current.[3]
    return count

Drag options to blanks, or click blank then click option'

Ahead

B+

Cnext

Ddata

Attempts:

3 left

💡 Hint

Common Mistakes

Starting from 'tail' which is not defined.

Using '=' instead of '+=' which overwrites count.

Using 'data' instead of 'next' to move forward.

Start from the head. Increase count by 1 each time you visit a node using count += 1. Move to the next node with current = current.next.