Get Length of Linked List in DSA Python - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a linked list?

A linked list is a chain of nodes where each node holds data and a link (pointer) to the next node. It is like a treasure hunt where each clue leads to the next.

beginner

How do you find the length of a linked list?

Start at the first node and move to the next node one by one, counting each node until you reach the end (null). The count is the length.

intermediate

Why can't we use indexing to find length in a linked list like arrays?

Linked lists don't store elements in continuous memory, so we can't jump to a position directly. We must visit each node to count.

intermediate

What is the time complexity of finding the length of a linked list?

It is O(n), where n is the number of nodes, because we must visit each node once to count.

beginner

Show the Python code snippet to get the length of a linked list.

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

def get_length(head):
    count = 0
    current = head
    while current:
        count += 1
        current = current.next
    return count

What does each node in a linked list contain?

A Only data

B Only a pointer to the next node

C Data and a pointer to the next node

D Data and index number

Each node stores data and a pointer to the next node to form the chain.

How do you know you reached the end of a linked list?

A When the next pointer is null

B When the data is zero

C When the index is last

D When the node points to itself

The last node's next pointer is null, indicating the end.

What is the time complexity to find the length of a linked list with n nodes?

A O(1)

B O(n)

C O(log n)

D O(n^2)

You must visit each node once, so time is proportional to n.

Why can't we directly access the 5th node in a linked list?

A Because nodes are not stored in continuous memory

B Because the 5th node is hidden

C Because linked lists do not have indexes

D Because linked lists are sorted

Nodes are scattered in memory, so we must follow links one by one.

What variable is commonly used to keep track of the count while finding length?

A size

B length

C index

D count

A variable like 'count' is used to increment as we visit each node.

Explain step-by-step how to find the length of a linked list.

Think of walking through a chain counting each link.

Write a simple Python function to get the length of a linked list and explain how it works.

Use a while loop and a counter variable.