Infosys Interview Experience
Infosys Interview Experience for Fresher Specialist Programmer, Dec 2025
Specialist Programmer
Fresher
Campus
14 Months
6 CPI and above, 60% or above in 10th,12th, no active backlogs (Salary Package: 10 lakh - fixed + 1 lakh joining bonus)
Computer Science Engineering
2 Rounds
Application Experience
I applied for the opportunity through the on-campus placement process at Motilal Nehru National Institute of Technology (MNNIT), Allahabad. After submitting my application through the college placement portal, I was shortlisted based on the eligibility criteria. The recruitment process began with an online assessment that tested aptitude, logical reasoning, and basic programming skills. Candidates who cleared the assessment were then shortlisted for the interview rounds. After successfully qualifying for the test, I was invited to the technical and HR interview stages conducted as part of the campus recruitment process, which eventually led to my selection.
Preparation
Topics Prepared: Data Structures and Algorithms, Object-Oriented Programming, Operating Systems, Database Management Systems, REST API Design
Preparation Tips
Tip 1: Practice data structures and algorithms problems consistently on coding platforms to improve problem-solving speed and logical thinking. Tip 2: Build real-world full-stack projects using technologies like React, Node.js, Express, and databases to strengthen practical development skills. Tip 3: Gain hands-on experience through internships and focus on understanding backend concepts such as REST APIs, database design, and system workflows.
Resume Tips
Tip 1: Include 2–3 strong projects that clearly demonstrate your technical skills, technologies used, and the impact or features you implemented. Tip 2: Mention internships, achievements, and coding platform ratings to showcase practical experience and problem-solving ability.
Interview Rounds (2)
Detailed breakdown of each evaluation round, questions asked, and candidate approaches.
Round 1 — Online Coding Interview
The round was conducted during the daytime as part of the scheduled on-campus placement process. The environment was professional and well-organized, with candidates waiting in sequence for their turn. Overall, the atmosphere was slightly nervous but also motivating, as everyone was eager to perform well. The interviewer was friendly and professional, which helped create a comfortable environment for discussion. They were attentive while listening to answers and encouraged clear explanations of concepts and experiences. Overall, the interaction felt like a constructive technical discussion rather than a stressful interrogation.
Problems & Questions Asked (4)
Making The Largest Island
You are given an 'n' x 'n' binary matrix 'grid' . You are allowed to change at most one '0' to be '1'. Your task is to find the size of the largest island in the grid after applying this operation. Note: An island is a 4-directionally (North, South, East, West) connected group of 1s. Example: Input: 'grid' = [[1,0], [0,1]] Output: 3 Explanation: We can change the 0 at (0,1) to 1 and get an island of size 3. Input format: The first line of each test case contains an integer 'n', representing the number of rows and columns in 'grid'. Each of the next 'n' lines contain 'n' elements each denoting the values of the grid. Output format: Return the largest size of the island in the grid after applying the given operation at most once. Note: You do not need to print anything, it has already been taken care of. Just implement the given function.
Use DFS/BFS with component labeling and hashing to calculate island sizes and evaluate the effect of converting each water cell. The time complexity should be approximately O(n × m).
Sum Paths
You are given a binary tree with 'N' nodes. Each node has an integer value associated with it. You are also given an integer 'Target'. Your task is to determine the total number of different paths such that the sum of values of nodes in each path equals 'Target'. Note : A path may or may not start at the root of the tree. A path may or may not end on a leaf node. You are allowed to travel only downwards. This means after visiting any node, you are allowed to visit only its children. Input Format : The first line contains an integer 'T', which denotes the number of test cases or queries to be run. Then, the 'T' test cases follow. The first line of each test case contains a single integer, 'Target', as described in the problem statement. The second line of each test case contains elements of the binary tree in the level order form. The line consists of values of nodes separated by a single space. In case a node is null, we take -1 in its place. For example, the input for the tree depicted in the below image would be : 6 -3 3 -1 -1 -1 -1 Explanation : Level 1 : The root node of the tree is 6 Level 2 : Left child of 6 = -3 Right child of 6 = 3 Level 3 : Left child of -3 = null (-1) Right child of -3 = null (-1) Left child of 3 = null (-1) Right child of 3 = null (-1) The first not-null node (of the previous level) is treated as the parent of the first two nodes of the current level. The second not-null node (of the previous level) is treated as the parent node for the next two nodes of the current level and so on. The input ends when all nodes at the last level are null (-1). Note : The above format was just to provide clarity on how the input is formed for a given tree. The sequence will be put together in a single line separated by a single space. Hence, for the above-depicted tree, the input will be given as: 6 -3 3 -1 -1 -1 -1 Output Format : For each test case, print an integer, denoting the number of different paths such that the sum of values of nodes in each path equals K. Output for each test case will be printed in a separate line. Note : You do not need to print anything. It has already been taken care of. Just implement the given function. Constraints : 1 <= T <= 100 1 <= N <= 5000 1 <= Target <= 10^9 -10^9 <= node data <= 10^9, , (where node data != -1). Time Limit: 1sec
Use Depth-First Search (DFS) and compute the maximum gain from the left and right subtrees at every node. While traversing, keep updating a global maximum for the best path sum found so far. Time Complexity: O(N) Space Complexity: O(H), where H is the height of the tree.
Travelling Salesman Problem
Given a list of cities numbered from 0 to N-1 and a matrix 'DISTANCE' consisting of 'N' rows and 'N' columns denoting the distances between each pair of cities, what is the shortest possible route that visits each city exactly once and returns to the starting city? Input Format : The first line contains a single integer ‘T’ denoting the number of test cases. The test cases are as follows. The first line of each test case contains an integer ‘N’, where ‘N’ denoting the number of the cities. The next ‘N’ lines of each test case contain ‘N’ space-separated integers “DISTANCE[i][j]”, where DISTANCE[i][j] denotes the distance to jth city from the ith city. Output Format : For each test case, return the minimum distance of the shortest possible route which visits each city exactly once and returns to the starting city. Note : You don’t need to print anything; It has already been taken care of. Just implement the given function. Constraints : 1 <= T <= 5 2 <= N <= 16 0 <= DISTANCE[i][j] <= 10^9 Time Limit: 1 sec
Use Dynamic Programming with bitmasking, where: dp[mask][i] represents the minimum cost to visit all cities in the given mask and end at city i. Transition: dp[mask][i] = min(dp[mask ^ (1 << i)][j] + cost[j][i])
Longest Substring with At Most K Distinct Characters
You are given a string 'str' and an integer ‘K’. Your task is to find the length of the largest substring with at most ‘K’ distinct characters. For example: You are given ‘str’ = ‘abbbbbbc’ and ‘K’ = 2, then the substrings that can be formed are [‘abbbbbb’, ‘bbbbbbc’]. Hence the answer is 7. Input Format: The first line of input contains the integer ‘T’ representing the number of test cases. The first line of each test case contains one integer, ‘K’, representing the maximum number of unique characters allowed in the string. The second line of each test case contains a single string ‘str’ representing the given string. Output Format: For each test case, print a single integer representing the length of largest substring that can be formed with at most ‘K’ unique characters. Print a separate line for each test case. Constraints: 1 <= T <= 10 1 <= K <= 26 1 <= |str| <= 10^6 The string str will contain only lowercase alphabets. Time Limit: 1 sec Note: You do not need to print anything. It has already been taken care of. Just implement the function.
Use the Sliding Window technique with a HashMap/Frequency Array to maintain the count of characters inside the window. Expand the right pointer to include characters and shrink the left pointer whenever the number of distinct characters exceeds k.
Round 2 — Face to Face
The round was conducted during the daytime as part of the scheduled campus recruitment process. The environment was professional and slightly tense, as many candidates were waiting for their turn, but it was overall well-organized. The round was a mixed technical and HR discussion, where the interviewer asked questions related to fundamentals, projects, and the general problem-solving approach, along with some HR questions about background, experiences, and career goals. The interviewer was friendly and supportive, which helped maintain a comfortable conversation and allowed me to explain my answers clearly. Overall, the interaction felt more like a discussion to understand my knowledge, communication skills, and problem-solving mindset.
Problems & Questions Asked (5)
Counting Sort
Ninja is studying sorting algorithms. He has studied all comparison-based sorting algorithms and now decided to learn sorting algorithms that do not require comparisons. He was learning counting sort, but he is facing some problems. Can you help Ninja implement the counting sort? For example: You are given ‘ARR’ = {-2, 1, 2, -1, 0}. The sorted array will be {-2, -1, 0, 1, 2}. Input Format: The first line contains an integer 'T' which denotes the number of test cases. The first line of each test case contains an integer ‘N’ representing the length of the ‘ARR’ array. The second line of each test case contains ‘N’ space-separated integers representing the ‘ARR’ array. Output Format: For each test case, print the sorted array. The output of each test case will be printed in a separate line. Constraints: 1 <= T <= 10 1 <= N <= 5000 -10^4 <= ARR[i] <= 10^4 Time limit: 1 sec Note: You do not need to input or print anything, as it has already been taken care of. Just implement the given function.
Step 1: I first understood that all elements lie within a limited range, which makes Counting Sort an efficient approach compared to comparison-based sorting algorithms. Step 2: I created a count array to store the frequency of each element in the input array. Step 3: I traversed the original array and updated the frequency of each number in the count array. Step 4: After storing the frequencies, I computed the prefix sums in the count array to determine the correct positions of elements in the sorted array. Step 5: Finally, I constructed the sorted output array using the count information and returned the sorted result.
Database Concepts
Explain the concept of transaction isolation levels in DBMS. What problems (dirty reads, non-repeatable reads, phantom reads) occur at each level, and how do databases prevent them? What is database normalization ? Explain different normal forms (1NF, 2NF, 3NF, BCNF) with examples, and when denormalization might be preferred in real systems. Explain how indexing works in databases. What is the difference between clustered and non-clustered indexes, and how do they affect query performance?
Tip 1: Focus on understanding core DBMS concepts such as transactions, normalization, indexing, and concurrency control, rather than memorizing definitions. Tip 2: Practice SQL queries and database design problems regularly to strengthen your practical understanding. Tip 3: Study real-world database scenarios, such as ACID properties, query optimization, and indexing strategies, to answer conceptual interview questions clearly.
URL Design
Explain the database schema you designed for the URL Shortener system. How did you store the original URL and short code, and handle redirection efficiently? How would you design a URL Shortener to handle millions of requests? Explain how database indexing and caching can improve the performance of redirection queries.
Tip 1: Understand how to design efficient database schemas for applications like URL shorteners (e.g., unique short codes, indexing on short URLs). Tip 2: Practice SQL queries and database operations such as insert, lookup, and indexing, as these are common in backend systems. Tip 3: Learn basic system design concepts like caching, hashing, and database indexing to explain how services like URL shorteners scale.
HR questions
Why do you want to join Infosys? Tell me about a time during your college life when you faced a difficulty and how you solved it. I was part of the Dramatics Club at MNNIT. Have you ever faced any conflicts, and how did you resolve them?
Tip 1: Be Honest with your answers.
Selection Perspective
I believe I was selected because I had a good balance of strong fundamentals and practical experience. My preparation in core subjects like data structures, OOP, and databases helped me confidently explain concepts, while my projects and internship experience demonstrated that I could apply these concepts in real-world scenarios. I also focused on clearly explaining my thought process and being honest about what I knew and what I was still learning. Overall, my consistency in problem-solving, hands-on development experience, and clear communication during the process played an important role in my selection.
Key Preparation Tips
Prepare DSA thoroughly.
Practice aptitude and puzzle-based questions.
Have at least two good projects on your resume.
Be prepared to explain your projects clearly.
Practice coding problems involving Arrays, Binary Search, DP and Recursion.
Prepare common HR questions such as Tell me about yourself and Who is your role model?
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