Blind 75 Questions with Answers
What is the Blind 75 list? It’s a curated set of 75 coding questions that are considered crucial for coding interviews. The list was curated by Yangshun Tay, who used it during his own job hunt to focus on the most important questions. The list was shared on Blind and LeetCode forums, where it gained popularity and was named "Blind 75". Over time, Blind 75 became popular as a quick roadmap for interview prep because it balances breadth and depth of topics.
Benefits of the Blind 75 list:
- Focused Practice: The list helps you focus on the most important questions, saving time and effort.
- Variety of Problems: The list covers a wide range of topics and problem types, providing comprehensive interview preparation.
- Preparation Schedule: The list is spread across different data structures and algorithmic techniques, helping you manage your preparation time effectively.
- Real Interview Scenario: You are advised to treat the practice like a real coding interview, which helps in building the right mindset and approach for actual interviews.
How this list helps in interview prep:
- Understanding Key Concepts: The list covers a variety of topics, helping engineers understand key concepts and algorithms.
- Improving Problem-Solving Skills: Regular practice with these questions can help improve problem-solving and coding skills.
- Building Confidence: By practicing with these important questions, engineers can build confidence for their coding interviews.
- Performance Tracking: The list can be used to track progress and identify areas that need more focus.
Blind 75 Questions:
Blind 75 has become a must-do list for coding interviews, Below is the complete Blind 75 list categorized by topic, along with practice links and solution links for each problem.
Sequences
Sequence-based questions in the Blind 75 focus on problems involving ordered data like arrays and strings. These test your understanding of patterns, iteration, and techniques like sliding windows and two pointers (e.g., Best Time to Buy and Sell Stock, Longest Substring Without Repeating Characters).
Question | Difficulty | Practice | Solution |
|---|---|---|---|
| 1. Two Sum | Easy | Link | Link |
| 2. Contains Duplicate | Easy | Link | Link |
| 3. Best Time to Buy and Sell Stock | Easy | Link | Link |
| 4. Valid Anagram | Medium | Link | Link |
| 5. Valid Parentheses | Medium | Link | Link |
| 6. Maximum Subarray | Medium | Link | Link |
| 7. Product of Array Except Self | Medium | Link | Link |
| 8. 3Sum | Medium | Link | Link |
| 9. Merge Intervals | Medium | Link | Link |
| 10. Group Anagrams | Medium | Link | Link |
| 11. Maximum Product Subarray | Medium | Link | Link |
| 12. Search in Rotated Sorted Array | Medium | Link | Link |
Data Structures
This category includes problems centered on fundamental data structures such as arrays, hash maps, and sets. These questions build a strong foundation for solving more complex problems efficiently (e.g., Two Sum, Valid Anagram, Group Anagrams).
Question | Difficulty | Practice | Solution |
|---|---|---|---|
| 1. Reverse a Linked List | Easy | Link | Link |
| 2. Detect Cycle in a Linked List | Easy | Link | Link |
| 3. Container With Most Water | Medium | Link | Link |
| 4. Find Minimum in Rotated Sorted Array | Medium | Link | Link |
| 5. Longest Repeating Character Replacement | Medium | Link | Link |
| 6. Longest Substring Without Repeating Characters | Medium | Link | Link |
| 7. Number of Islands | Medium | Link | Link |
| 8. Remove Nth Node From End Of List | Medium | Link | Link |
| 9. Palindromic Substrings | Medium | Link | Link |
| 10. Pacific Atlantic Water Flow | Medium | Link | Link |
| 11. Minimum Window Substring | Medium | Link | Link |
Non-Linear Data Structures
Non-linear data structure questions explore trees and graphs—structures where elements are not arranged sequentially. These problems often test traversal techniques, recursion, and understanding of hierarchical or networked relationships (e.g., Lowest Common Ancestor, Number of Islands).
Question | Difficulty | Practice | Solution |
|---|---|---|---|
| 1. Invert/Flip Binary Tree | Easy | Link | Link |
| 2. Validate Binary Search Tree | Medium | Link | Link |
| 3. Non-overlapping Intervals | Medium | Link | Link |
| 4. Construct Binary Tree from Preorder and Inorder Traversal | Medium | Link | Link |
| 5. Top K Frequent Elements | Medium | Link | Link |
| 6. Clone Graph | Medium | Link | Link |
| 7. Task Scheduler | Medium | Link | Link |
| 8. Serialize and Deserialize Binary Tree | Hard | Link | Link |
| 9. Binary Tree Maximum Path Sum | Hard | Link | Link |
| 10. Maximum Depth of Binary Tree | Easy | Link | Link |
| 11. Same Tree | Easy | Link | Link |
| 12. Binary Tree Level Order Traversal | Medium | Link | Link |
| 13. Encode and Decode Strings | Medium | Link | Link |
More Data Structures
This category dives into advanced or compound data structures like heaps, stacks, queues, and tries. These problems test your ability to use the right tool for the job in more complex algorithmic scenarios (e.g., Kth Largest Element in an Array, Implement Trie).
Question | Difficulty | Practice | Solution |
|---|---|---|---|
| 1. Subtree of Another Tree | Easy | Link | Link |
| 2. Lowest Common Ancestor of BST | Medium | Link | Link |
| 3. Implement Trie (Prefix Tree) | Medium | Link | Link |
| 4. Add and Search Word | Medium | Link | Link |
| 5. Kth Smallest Element in a BST | Medium | Link | Link |
| 6. Merge K Sorted Lists | Hard | Link | Link |
| 7. Find Median from Data Stream | Hard | Link | Link |
| 8. Insert Interval | Medium | Link | Link |
| 9. Longest Consecutive Sequence | Medium | Link | Link |
| 10. Word Search II | Hard | Link | Link |
| 11. Meeting Rooms | Easy | Link | Link |
| 12. Meeting Rooms II | Medium | Link | Link |
| 13. Graph Valid Tree | Medium | Link | Link |
| 14. Number of Connected Components in an Undirected Graph | Medium | Link | Link |
| 15. Alien Dictionary | Hard | Link | Link |
Dynamic Programming
Dynamic Programming questions in the Blind 75 cover classic problems like computing sequences and optimal substructures (e.g., Climbing Stairs, Coin Change, etc.), building DP intuition.
Question | Difficulty | Practice | Solution |
|---|---|---|---|
| 1. Climbing Stairs | Easy | Link | Link |
| 2. Coin Change | Medium | Link | Link |
| 3. Longest Increasing Subsequence | Medium | Link | Link |
| 4. Combination Sum | Medium | Link | Link |
| 5. House Robber | Medium | Link | Link |
| 6. House Robber II | Medium | Link | Link |
| 7. Decode Ways | Medium | Link | Link |
| 8. Unique Paths | Medium | Link | Link |
| 9. Jump Game | Medium | Link | Link |
| 10. Word Break | Medium | Link | Link |
Frequently Ask Questions
1.
What is Blind 75 and why is it beneficial for coding interview prep?
Blind 75 is a curated list of 75 essential coding interview questions, originally compiled by an experienced Meta engineer after solving hundreds of LeetCode problems. It covers all the fundamental data structure and algorithm topics (arrays, graphs, dynamic programming, etc.) through high-quality, frequently asked questions that capture common patterns seen in real interviews.
The idea is to focus on quality over quantity – by mastering these 75 representative problems, you’ll develop the skills and pattern recognition needed to tackle many variations of questions that tech companies ask. In short, Blind 75 became popular as an efficient study roadmap because it saves time (no need to sift through thousands of questions) and ensures you practice the most impactful problems for interview success.
The idea is to focus on quality over quantity – by mastering these 75 representative problems, you’ll develop the skills and pattern recognition needed to tackle many variations of questions that tech companies ask. In short, Blind 75 became popular as an efficient study roadmap because it saves time (no need to sift through thousands of questions) and ensures you practice the most impactful problems for interview success.
2.
Is Blind 75 suitable for beginners who are new to coding interviews?
Yes. Blind 75 is often recommended as a starting point for those new to coding interviews because it provides a structured set of core problems to work through. If you have basic knowledge of programming and data structures, this list is very beginner-friendly in terms of guiding your practice. In fact, Blind 75 is considered a “high-value, low-friction” approach for newcomers – it helps you build up fundamental problem-solving skills without overwhelming you. Before you begin, it’s wise to brush up on basic data structures and algorithms (like arrays, linked lists, trees, BFS/DFS, etc.) so you can get the most out of each problem. Overall, many novices use Blind 75 as a roadmap to gain confidence and competency in coding interviews.
3.
How should I approach solving the Blind 75 problems as a beginner?
To get the most out of Blind 75, try the following approach steps:
- Review the basics first: Ensure you understand foundational data structures and algorithms before diving in. This will help you grasp the solutions more easily.
- Focus on one topic at a time: Blind 75 covers multiple categories of problems. It’s effective to tackle one category or topic area at a time. For example, solve all the array problems first, then move on to linked list problems, and so on. This way, you reinforce patterns within a category before switching contexts.
- Take notes on patterns:After solving each problem, jot down the key pattern or technique used. Each Blind 75 question illustrates a common strategy (for instance, using sorting to solve interval problems) – writing these insights down will help you remember them.
- Practice active recall by revisiting problems: Don’t just solve a problem once and forget about it. Come back to the same question after a few days or a week and try to solve it again from scratch. This repetition solidifies your learning and improves your speed in recognizing solutions.
- Simulate real interview conditions: As you progress, practice writing out code on a whiteboard or paper (since many interviews are not on a computer). Also, start timing yourself when solving problems to get used to the pressure of a timed interview setting. For example, give yourself ~20 minutes per medium problem and see if you can arrive at a solution within that time. This will train you to think and code under time constraints. By following these steps, beginners can gradually build up their problem-solving skills and confidence while avoiding burnout during the Blind 75 journey.
4.
What resources or features does your platform provide to help with Blind 75?
Our platform offers several unique features to support you as you work through the Blind 75 list. First, we provide detailed solutions and explanations for each of the 75 problems – after you attempt a question, you can review our step-by-step solution to understand the optimal approach. We also include helpful hints for tricky problems, so beginners can get guided nudges if they’re stuck without immediately seeing the full solution. In addition, the platform has an integrated coding workspace where you can run and test your code for each problem, which makes practicing more convenient. We offer progress tracking tools as well – you can mark problems as solved, keep notes, and monitor your overall completion progress. These features (our solutions, hints, and interactive tools) are designed to make your Blind 75 practice more effective by providing learning support and keeping you organized and motivated.
5.
Is completing Blind 75 enough to prepare for coding interviews?
Completing Blind 75 will give you a strong foundation in the most commonly asked coding questions, and for many entry-level or standard software engineering interviews, it is often sufficient preparation. There are numerous testimonials of candidates who landed offers at top companies (Google, Meta, Amazon, etc.) by focusing on Blind 75, because it trains you in the fundamental patterns needed for those interviews. However, it’s important to note that Blind 75 is a foundation, not the entire building of interview prep. If you are aiming for more senior-level roles or companies that have additional rounds (like system design or domain-specific questions), you will need to go beyond Blind 75. In those cases, after finishing Blind 75, you should practice system design problems, cover more advanced or specialized algorithms, and perhaps work on behavioral interview skills. In summary, Blind 75 is an excellent starting point and often enough for beginners’ coding interviews, but be prepared to supplement it with more practice on advanced topics as your target role requires.
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