Interview Bite

Why Basic DSA Questions Matter in Interviews

Data Structures and Algorithms (DSA) form the core of technical interviews at top tech companies like Google, Amazon, and Microsoft. Even as a fresher, you’ll be tested on:

✔ Problem-solving approach
✔ Efficiency (Big-O notation)
✔ Implementation of basic data structures
✔ Algorithm design skills

Mastering these fundamentals increases your chances of landing a high-paying software engineering job.

50 Basic DSA Interview Questions & Answers

1. Arrays & Strings (Most Common!)

1. How to reverse an array? (Ans: Two-pointer technique)
2. Find the missing number in 1 to N array. (Ans: Sum formula or XOR method)
3. Check if a string is a palindrome. (Ans: Compare start and end characters)
4. Remove duplicates from a sorted array. (Ans: Two-pointer approach)
5. Find the largest element in an array. (Ans: Linear search or sorting)

2. Linked Lists

6. Reverse a linked list. (Ans: Iterative or recursive method)
7. Detect a loop in a linked list. (Ans: Floyd’s Cycle Detection)
8. Find the middle of a linked list. (Ans: Fast & slow pointer)

3. Stacks & Queues

9. Implement stack using arrays. (Ans: LIFO operations with array)
10. Check balanced parentheses. (Ans: Stack-based validation)

4. Trees (Binary Trees & BST)

11. Find height of a binary tree. (Ans: Recursive DFS)
12. Check if a tree is a BST. (Ans: Inorder traversal should be sorted)
13. Level order traversal (BFS). (Ans: Queue-based approach)

5. Sorting & Searching

14. Implement Binary Search. (Ans: Divide & conquer on sorted array)
15. Difference between QuickSort & MergeSort. (Ans: QuickSort is in-place, MergeSort is stable)

6. Recursion & Dynamic Programming

16. Fibonacci series using recursion. (Ans: fib(n) = fib(n-1) + fib(n-2))
17. What is memoization? (Ans: Storing results to avoid recomputation)

7. Hashing & Sliding Window

18. First non-repeating character in a string. (Ans: Hash map tracking counts)
19. Longest substring without repeating characters. (Ans: Sliding window technique)

8. Time & Space Complexity (Big-O)

20. Time complexity of Bubble Sort? (Ans: O(n²))
21. Difference between O(1) and O(n) space? (Ans: Constant vs linear memory)
22. How to Prepare for DSA Interviews?
    Practice Daily – Solve 1-2 problems on LeetCode/HackerRank
    Understand Patterns – Learn standard approaches (Two Pointers, Sliding Window, etc.)
    Mock Interviews – Try Pramp or InterviewBit for real-time practice
    Revise Complexity – Always analyze time/space complexity
    
    FAQs (Frequently Asked Questions)
    1. Which DSA topics are most important for freshers?
    Arrays, Strings, Linked Lists, Binary Trees, and Sorting Algorithms cover 80% of interviews.
    2. How many DSA questions should I practice?
    Aim for 100+ quality problems covering all patterns.
    3. Is DSA required for front-end roles?
    Yes! Companies like Meta ask DSA even for front-end positions.
    
    Final Tips to Crack DSA Interviews
    ✅ Start with easy problems before moving to medium/hard
    ✅ Focus on problem-solving patterns, not memorization
    ✅ Time yourself – Many interviews are timed (30-45 mins per question)
    ✅ Explain your approach – Interviewers value communication
    Need a structured plan? Download our free 30-day DSA roadmap! 🚀
    
    Which DSA topic do you find most challenging? Let us know in the comments! #DSA #CodingInterviews