Search for a Value in 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 to the next node. It is like a treasure hunt where each clue leads to the next.

beginner

How do you search for a value in a linked list?

Start at the first node and check its value. If it matches, stop. If not, move to the next node. Repeat until you find the value or reach the end.

beginner

What happens if the value is not found in the linked list?

You reach the end of the list (null) without finding the value. This means the value is not in the list.

intermediate

Why can't we directly access a node in a linked list like in an array?

Because linked lists are connected by links, not by index. You must follow the links from the start to reach a node.

intermediate

What is the time complexity of searching a value in a linked list?

It is O(n), where n is the number of nodes, because you may need to check each node once.

What do you check first when searching for a value in a linked list?

A The value of the current node

B The value of the last node

C The total number of nodes

D The index of the node

You always check the value of the current node before moving on.

If the value is not found, where does the search end in a linked list?

A At the first node

B At the last node

C At the middle node

D At null (end of the list)

The search ends when you reach null, meaning no more nodes.

What is the main reason linked lists do not support direct access by index?

A Nodes have no values

B Nodes are not stored in continuous memory

C Nodes are sorted

D Nodes are stored in arrays

Linked list nodes are scattered in memory and connected by links.

What is the worst-case time complexity to find a value in a linked list with n nodes?

A O(1)

B O(log n)

C O(n)

D O(n log n)

You may need to check all n nodes in the worst case.

Which of these is NOT a step in searching a linked list?

A Jump directly to the middle node

B Check the node's value

C Start at the head node

D Move to the next node if no match

You cannot jump directly; you must follow links one by one.

Explain how to search for a value in a linked list step-by-step.

Think of walking through a chain of friends asking if they have a message.

Why is searching a linked list slower than searching an array by index?

Imagine looking for a book in a pile versus a shelf with numbered slots.