50 Most Asked DSA Interview Questions to Practice in 2025

Are you preparing for coding interviews and feeling overwhelmed by the endless list of DSA problems? You're not alone! 

With thousands of DSA questions available online, knowing where to start can be confusing. Should you solve 500 problems or focus on the most important ones?

The truth is, you don't need to solve every problem out there. Most tech companies ask variations of the same core DSA concepts. By mastering these top 50 DSA interview questions, you'll be well-prepared for 80% of the coding interviews you'll face. ✅

This guide covers the most frequently asked DSA questions across all major topics - from basic arrays and strings to advanced dynamic programming and graph problems. These questions have been asked at top companies like Google, Amazon, Microsoft, Facebook, and many others.

Whether you're a fresher looking for your first job or an experienced developer switching companies, these DSA questions form the foundation of technical interviews. 

Let's dive into the most important DSA problems you should practice. 👇

Top 50 DSA Interview Questions You Need to Practice

🔹 Arrays

1. Two Sum (LeetCode #1) – Amazon, Google
2. Best Time to Buy and Sell Stock (LeetCode #121) – Apple, Amazon
3. Majority Element (LeetCode #169) – Adobe, Goldman Sachs
4. Maximum Subarray (LeetCode #53) – Microsoft, AmazonMerge Intervals (LeetCode #56) – Facebook, Google
5. Product of Array Except Self (LeetCode #238) – Amazon, Facebook
6. Set Matrix Zeroes (LeetCode #73) – Flipkart, Adobe

🔹 Strings

1. Valid Anagram (LeetCode #242) – Amazon, PayPal
2. Longest Substring Without Repeating Characters (LeetCode #3) – Google, Microsoft
3. Group Anagrams (LeetCode #49) – Facebook, Amazon
4. Longest Palindromic Substring (LeetCode #5) – Adobe, Microsoft
5. Valid Parentheses (LeetCode #20) – Amazon, Google
6. Implement strStr() (LeetCode #28) – Oracle, TCS

🔹 Linked Lists

1. Reverse Linked List (LeetCode #206) – Google, Amazon
2. Merge Two Sorted Lists (LeetCode #21) – Microsoft, Infosys
3. Linked List Cycle (LeetCode #141) – Amazon, Adobe
4. Remove Nth Node From End of List (LeetCode #19) – Facebook, Oracle
5. Add Two Numbers (LeetCode #2) – Apple, Microsoft
6. LRU Cache (LeetCode #146) – Amazon, Flipkart

🔹 Trees

1. Maximum Depth of Binary Tree (LeetCode #104) – Amazon, PayPal
2. Same Tree (LeetCode #100) – Microsoft, Oracle
3. Invert Binary Tree (LeetCode #226) – Google, Apple
4. Lowest Common Ancestor of a BST (LeetCode #235) – Facebook, Amazon
5. Serialize and Deserialize Binary Tree (LeetCode #297) – Google, Facebook
6. Diameter of Binary Tree (LeetCode #543) – Amazon, Adobe

🔹 Graphs

1. Number of Islands (LeetCode #200) – Facebook, Amazon
2. Clone Graph (LeetCode #133) – Google, Bloomberg
3. Course Schedule (LeetCode #207) – Amazon, Microsoft
4. Pacific Atlantic Water Flow (LeetCode #417) – Google, Apple
5. Word Ladder (LeetCode #127) – Facebook, Adobe

🔹 Dynamic Programming

1. Climbing Stairs (LeetCode #70) – Amazon, Accenture
2. House Robber (LeetCode #198) – Apple, Microsoft
3. Coin Change (LeetCode #322) – Google, Amazon
4. Longest Increasing Subsequence (LeetCode #300) – Amazon, Adobe
5. Partition Equal Subset Sum (LeetCode #416) – Facebook, Oracle

🔹 Recursion & Backtracking

1. Subsets (LeetCode #78) – Microsoft, Google
2. Combination Sum (LeetCode #39) – Amazon, Adobe
3. Permutations (LeetCode #46) – Google, Accenture
4. Word Search (LeetCode #79) – Apple, Facebook
5. N-Queens (LeetCode #51) – Google, Microsoft

🔹 Searching & Sorting

1. Binary Search (LeetCode #704) – Amazon, Google
2. Search in Rotated Sorted Array (LeetCode #33) – Facebook, Microsoft
3. Kth Largest Element in an Array (LeetCode #215) – Amazon, Flipkart
4. Merge Sort (Conceptual Implementation) – Infosys, Cognizant
5. Quick Sort (Conceptual Implementation) – Wipro, Tech Mahindra

🔹 Miscellaneous / Tricky

1. Rotate Image (LeetCode #48) – Facebook, Amazon
2. Spiral Matrix (LeetCode #54) – Microsoft, Adobe
3. Find Median from Data Stream (LeetCode #295) – Google, Facebook
4. Sliding Window Maximum (LeetCode #239) – Amazon, Apple
5. LFU Cache (LeetCode #460) – Google, Amazon

Also read: Top 100 Coding Interview Questions for 2025

How to Practice These DSA Questions the Right Way?

Now that you have the questions, it’s time to practice like it's the real thing, not just solve them for the sake of it. Here’s what you should focus on while solving:

• Are you writing clean and optimised code?
• Do you catch all possible edge cases?
• Can you explain your approach out loud, like in a real interview?
• Are you finishing within a time limit?

Practising blindly won’t help. You need feedback, structure, and time pressure - just like an actual interview.

That’s exactly what this Mentor AI Chrome Extension helps with.

🧩 What is it?

A free Coding companion designed to improve your DSA skills in real-time. It offers four core functions: Real-Time Feedback, Interview Mode, Test Case Discussion, and Approach Guidance.

💡 Real-Time Feedback While You Code

• Watches your code and flags inefficiencies, suggests optimisations and edge cases
• Works on all major coding platforms (no switching tabs)

⏱️ Practice in Interview Mode

When you're ready to simulate real interviews, just switch to Interview Mode.

• Solve a problem with a 20-minute timer
• Use the audio button to speak your thought process out loud, like you would in a real interview
• Get a detailed feedback report post-submission that consists of: Your strengths, weak areas, time/space complexity, tips to improve

🧪 Discuss More Test Cases & Approach

• Get help on creating and discussing tricky test cases

• Get a step-by-step breakdown of how to approach a problem
• Useful when you're stuck or want to compare with optimal approaches
• Great for improving problem-solving skills over time

Whether you’re solving your first DSA interview question or preparing for FAANG interviews, this tool gives you an edge and makes every practice session count.

Ready to ace your next coding interview?

FAQs on DSA Interview Prep

1. What are the most common DSA interview questions for freshers?

Freshers are usually asked basic DSA questions like:

• Reverse a string or linked list
• Find the maximum in an array
• Implement a stack or queue
• Check for balanced parentheses

These questions test your understanding of data structures and logic. Start with easy LeetCode problems to prepare well.

2. What are the top DSA questions I should prepare for in 2025?

The top DSA questions for 2025 focus on core concepts like arrays, strings, linked lists, trees, graphs, and dynamic programming.

Companies often ask problems like Two Sum, Longest Substring Without Repeating Characters, Merge Intervals, LRU Cache, and Number of Islands.

These questions test both your logic and coding speed.

3. How should experienced professionals prepare for DSA interviews?

For experienced candidates, DSA questions for interviews focus on solving medium to hard problems quickly.

Interviewers look for optimised solutions and coding speed. You should also prepare system design questions along with advanced DSA topics like Trees, Graphs, and DP.

4. How many DSA questions should I solve before the interviews?

Start with these 50 questions - they cover 80% of interview patterns. Once you've mastered these, you can expand to 100-150 total questions for additional practice.

The key is depth over breadth - thoroughly understanding these 50 is better than solving 200 random problems.

5. Are DSA interviews the same across all companies?

Not exactly. While the core DSA topics remain the same, top product-based companies like Google, Amazon, and Microsoft may go deeper into problem-solving and optimisation.

Start with general DSA questions for interviews, then switch to company-specific ones.

You can also connect 1:1 with senior SDEs on hiring panels from FAANG or top product-based companies and prepare for company-specific DSA interviews. 🚀

The first session is free, book here :)

Also read:

DSA Preparation - The Ultimate Guide to Crack DSA Interviews