Introduction
Linked list interview questions are a top concern for software engineering candidates preparing for coding rounds. If you’ve lost sleep over pointers, edge cases, or in-place reversals, this guide gives a focused, practical path through the Top 30 most common linked list interview questions you should prepare for. Read on for crisp definitions, clear strategies, and the exact Q&A pairs hiring teams expect. Prepare with intention, practice patterns, and learn how to explain solutions under pressure for better interview performance.
What are the Top 30 most common linked list interview questions you should prepare for?
Answer: These are the 30 core questions that appear most often across entry to senior-level technical interviews.
Hiring teams repeatedly test fundamentals like traversal, reversal, cycle detection, merging, and pointer manipulation. Below you’ll get concise questions and model answers that map to problem patterns—two-sentence definitions, algorithmic hints, and when to use each technique. Use these Q&A pairs to structure practice sessions and mock interviews so you can demonstrate clarity and correctness under time constraints. Takeaway: Mastering these 30 linked list interview questions builds a reliable base for most coding interviews.
Technical Fundamentals
Q: What is a linked list?
A: A linear data structure where each node holds data and a pointer to the next node, enabling dynamic insertion and deletion.
Q: What is a singly linked list vs. a doubly linked list?
A: A singly linked list has next pointers only; a doubly linked list has next and prev pointers for bidirectional traversal.
Q: How do you traverse a linked list?
A: Start at head, follow next pointers until null; track time O(n) and constant extra space for iterative traversal.
Q: How do you insert a node at the head of a linked list?
A: Create node, set node.next = head, update head = node; O(1) time insertion at head.
Q: How do you insert a node at the tail when you don't have a tail pointer?
A: Traverse to the last node then set last.next = newNode; O(n) time unless a tail pointer is maintained.
Q: How do you delete a node from a linked list when only given the node to delete?
A: Copy next node's value into current node and bypass next node; not possible for the last node with this trick alone.
Q: How do you reverse a singly linked list iteratively?
A: Use three pointers (prev, curr, next): iterate, reverse pointer, advance; O(n) time, O(1) space.
Q: How do you reverse a singly linked list recursively?
A: Recurse to tail, then on unwind set next.next = node and node.next = null; uses O(n) call stack.
Q: How do you detect a cycle in a linked list?
A: Use Floyd’s Tortoise and Hare: two pointers at different speeds meet if cycle exists; O(n) time, O(1) space.
Q: How do you find the start node of a cycle?
A: After detection, move one pointer to head and advance both at same speed until they meet; meeting node is cycle start.
Q: How do you remove a cycle in a linked list?
A: Find cycle start as above, track previous node in cycle and set previous.next = null to break the loop.
Q: How do you find the middle of a linked list?
A: Use slow and fast pointers; when fast reaches end, slow is at middle; handles even-length via defined convention.
Q: How to detect if two singly linked lists intersect?
A: Compare tail nodes by traversing both or align lengths then walk together to find first equal node reference.
Q: How to merge two sorted linked lists?
A: Use two pointers and a dummy head to splice nodes in increasing order; O(n+m) time, O(1) extra space.
Q: How do you remove duplicate nodes from a sorted linked list?
A: Traverse and skip nodes with equal values by adjusting next pointers; O(n) time, O(1) space.
Common Problem Patterns
Q: How to remove the Nth node from end of list in one pass?
A: Use two pointers spaced N nodes apart; advance until fast hits end, then adjust slow.next to remove target.
Q: How to check if a linked list is a palindrome?
A: Find middle, reverse second half, compare halves, then restore list; O(n) time, O(1) space if restored.
Q: How to add two numbers represented by linked lists (digits in reverse)?
A: Traverse both lists with carry, create result nodes; use dummy head for easy assembly, O(max(n,m)) time.
Q: How to rotate a linked list to the right by k places?
A: Connect tail to head to form a cycle, find new tail at length - k%length, break cycle; O(n) time.
Q: How to partition a linked list around value x?
A: Build two lists (less and greater/equal) and join them, preserving original relative order; O(n) time.
Q: How to flatten a multilevel linked list?
A: Use DFS or stack to splice child lists into main list while preserving next pointers; careful with pointers and null checks.
Q: How to copy a linked list with random pointers?
A: Interleave copied nodes with originals, set random pointers by referencing neighbors, then separate; O(n) time, O(1) extra.
Q: How to reverse nodes in k-group chunks?
A: Count k nodes, reverse the group with pointer ops, reconnect, repeat; handle remainder < k by leaving as-is.
Q: How to remove all nodes with a given value?
A: Use a dummy head and iterate, skipping nodes that match the value to rewire next pointers.
Q: How to detect the length of a cycle?
A: After Floyd detection, keep one pointer fixed and loop the other until meeting again, counting steps.
Q: How to find the intersection node when lists can be different lengths?
A: Advance longer list by length difference then advance both simultaneously until references match.
Q: How to implement an LRU cache using a linked list?
A: Combine a doubly linked list for ordering with a hash map for O(1) access and updates.
Q: How to merge k sorted linked lists efficiently?
A: Use a min-heap to merge in O(N log k) total time or divide-and-conquer merging for O(N log k) time.
Q: How to remove duplicates from an unsorted linked list?
A: Use a hash set to track seen values and remove repeats; O(n) time and O(n) space, or O(n^2) without extra space.
Q: What common pointer mistakes cause bugs in linked list interview questions?
A: Off-by-one errors, failing to update head/tail, not checking nulls before dereference, and incorrect loop termination conditions.
How to prepare and master linked list interview questions
Answer: Focused pattern practice, clear explanations, and timed mock problems are the fastest path to confidence.
Start by understanding node-level operations, then practice the common patterns above (two-pointer, reversal, cycle handling, grouping). Simulate interviews by explaining your approach aloud, stating edge cases, and sharing time-space tradeoffs. Use curated guides and cheat-sheets from trusted sources to structure practice—see resources from AlgoCademy, DesignGurus.io, and the Tech Interview Handbook for study plans and examples. Takeaway: Regular, focused practice of linked list interview questions with clear verbalization beats ad-hoc problem solving.
Coding patterns and templates for linked list interview questions
Answer: Recognize and rehearse four key patterns—two-pointer techniques, dummy head pattern, in-place reversal, and list splitting/merging.
Templates accelerate writing correct code under pressure: always consider dummy nodes for head manipulation, slow/fast pointers for mid/cycle detection, and iterative reversal primitives to reuse. Pair pattern recognition with time and space analysis; when asked “why” in interviews, cite complexity and edge-case handling. For deeper pattern walkthroughs and example-driven templates, review Interview Cake’s linked list concepts and GeeksforGeeks’ problem bank for variations and practice sets. Takeaway: Memorize and rehearse a few templates to cut coding time and avoid pointer errors during interviews.
Practice checklist for linked list interview questions
Answer: A short checklist keeps practice efficient and interview-ready.
Before coding, clarify input/output, ask about allowed modifications, note constraints (e.g., extra memory), list edge cases, and state complexity targets. During coding, narrate intent, use helper functions for repeating tasks (reverse sublist, find length), and run quick dry-runs on small lists. After coding, discuss restoration or side effects if the interviewer cares about preserving input. Takeaway: A consistent checklist transforms comfortable knowledge of linked list interview questions into interview-grade answers.
How Verve AI Interview Copilot Can Help You With This
Verve AI Interview Copilot provides real-time feedback on structure, clarity, and edge-case handling when you practice common linked list interview questions. It suggests step-by-step templates, asks follow-up clarifying questions you should voice in interviews, and highlights time/space trade-offs as you code or explain. Use Verve AI Interview Copilot to rehearse answers with simulated prompts and to receive adaptive hints when you get stuck. Verve AI Interview Copilot also offers tailored follow-ups that mimic interviewer probes, improving your explanation and confidence. This tool helps you refine concise, interview-ready responses while reducing stress.
What Are the Most Common Questions About This Topic
Q: Can Verve AI help with behavioral interviews?
A: Yes. It applies STAR and CAR frameworks to guide real-time answers.
Q: How long to prepare linked list topics?
A: Typically 2–4 weeks of focused practice for fundamentals and patterns.
Q: Are linked list questions language-specific?
A: No. Concepts map across Python, Java, and C++ with minor syntax changes.
Q: Which resources are best for a problem bank?
A: Use GeeksforGeeks, Tech Interview Handbook, and AlgoCademy for curated lists.
Q: How to avoid pointer bugs in interviews?
A: Verbally state invariants, use dummy nodes, and run short dry-runs.
What to study next after these linked list interview questions
Answer: After mastering the Top 30 linked list interview questions, expand to trees, heaps, and graph traversal patterns.
Linked list patterns often generalize to array two-pointer problems and tree recursion; build cross-data-structure fluency by solving variations that mix structures (e.g., lists inside trees or vice versa). Schedule mixed mock interviews to practice switching conceptual modes quickly. Takeaway: Use linked list mastery as a stepping stone to broader algorithmic confidence.
Recommended resources and reading
Answer: Use a mix of curated problem banks, concept guides, and mock interview platforms for comprehensive preparation.
For a practical study plan and problem walkthroughs, consult AlgoCademy’s linked list guide. For pattern-based videos and problem templates, see DesignGurus.io. For a concise cheatsheet and complexity notes, the Tech Interview Handbook and GeeksforGeeks’ top problems are invaluable. Takeaway: Pair problem banks with pattern study and timed mock interviews.
Conclusion
Mastering linked list interview questions combines clean templates, practiced verbal explanations, and steady exposure to edge cases—this guide’s Top 30 set builds that foundation. Focus on pattern recognition, clear narration, and O(n)/O(1) reasoning to improve interview performance and confidence. Try Verve AI Interview Copilot to feel confident and prepared for every interview.
