What are must-do linked list problems for coding interviews

Linked lists are a fundamental data structure often covered in coding interviews, especially for positions at tech companies like those in FAANG. Understanding how to manipulate linked lists is crucial, as it tests your knowledge of pointers, memory management, and the ability to handle edge cases. Here are some must-do linked list problems that are typically recommended for coding interviews. These problems are designed to cover a broad range of concepts from simple traversals to more complex manipulations like reversing or reordering linked lists.

1. Reverse a Linked List

• Concept: This problem tests your understanding of pointer manipulation and in-place reversal techniques.
• Variations: Reversing a singly linked list, a doubly linked list, or parts of a linked list.

2. Detect a Cycle in a Linked List

• Concept: This involves identifying a cycle in a linked list using algorithms like Floyd’s Cycle-Finding Algorithm (Tortoise and the Hare).
• Application: Useful for understanding two-pointer techniques.

3. Merge Two Sorted Linked Lists

• Concept: Merging two sorted linked lists into a single sorted linked list. It’s a fundamental problem that combines elements of both linked list manipulation and sorting logic.

4. Find the Intersection Point of Two Linked Lists

• Concept: The challenge is to find the point at which two linked lists intersect without modifying the linked lists.
• Application: Tests your ability to deal with complex linked list structures and use of pointers.

5. Remove N-th Node From End of List

• Concept: This requires efficient pointer manipulation to remove a node from the end of the list in one pass.
• Technique: Often solved using the two-pointer technique where one pointer starts after n-steps ahead.

6. Palindrome Linked List

• Concept: Checking if the contents of a linked list form a palindrome. This can involve reversing a linked list or using a fast and slow pointer approach.

7. Add Two Numbers Represented by Linked Lists

• Concept: You’re given two numbers represented by two linked lists, where each node contains a single digit. The digits are stored in reverse order.
• Challenge: Adding two such numbers and returning the sum as a linked list.

Searching and Reviewing Problems

To find these problems on platforms like Design Gurus, you can navigate through their courses related to data structures or specifically linked lists. Typically, these platforms categorize problems by difficulty and concept, which makes it easier to focus on specific areas needed for mastery in coding interviews.

How to Practice

• Understand the Problem: Make sure you fully understand the problem statement and requirements before you start coding.
• Write Pseudocode: Before implementing the solution, plan your approach using pseudocode.
• Implement Solutions: Write the code for your planned solution, then test it with various test cases.
• Review and Reflect: After solving the problem, review your approach and understand any mistakes or inefficiencies. Look at solutions or discussions provided in the course to gain additional insights.

Conclusion

Practicing these types of linked list problems will help you develop a strong understanding of linked lists and prepare you for related questions in technical interviews. Remember, the key to mastering linked list problems is as much about understanding the theory as it is about hands-on practice.