Infosys interview experience Real time questions & tips from candidates to crack your interview

Specialist Programmer

2 rounds | 8 Coding problems

Selected candidate experience

Interview preparation journey

Journey

I am currently a final-year student at Motilal Nehru National Institute of Technology (MNNIT), Allahabad. My journey toward securing an SDE-1 role at Infosys began with building strong programming fundamentals. Initially, I focused on learning core concepts such as data structures, algorithms, and problem-solving, while consistently practicing coding. Alongside this, I developed an interest in full-stack development and worked with technologies like React, Node.js, Express, and MongoDB to build practical projects. These experiences helped me understand how real-world software systems are designed and implemented. When the on-campus opportunity arose, I focused on strengthening my fundamentals, clearly explaining my projects, and demonstrating my problem-solving approach during the interview. This ultimately helped me secure the SDE-1 role.

Application story

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.

Why selected/rejected for the role?

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.

Preparation

Duration: 14 Months

Topics: Data Structures and Algorithms, Object-Oriented Programming, Operating Systems, Database Management Systems, REST API Design

Tip

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.

Application process

Where: Campus

Eligibility: 6 CPI and above, 60% or above in 10th,12th, no active backlogs (Salary Package: 10 lakh - fixed + 1 lakh joining bonus)

Resume tip

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

Round

Hard

Online Coding Interview

Duration180 minutes

Interview date5 Dec 2025

Coding problem4

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.

1. Making The Largest Island

Moderate

30m average time

70% success

0/80

Asked in companies

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.

Problem approach

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).

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2. Sum Paths

Moderate

30m average time

70% success

0/80

Asked in companies

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.

Problem approach

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.

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3. Travelling Salesman Problem

Hard

50m average time

50% success

0/120

Asked in companies

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?

Problem approach

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])

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4. Longest Substring with At Most K Distinct Characters

Moderate

20m average time

80% success

0/80

Asked in companies

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.

Problem approach

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.

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Round

Medium

Face to Face

Duration60 minutes

Interview date6 Dec 2025

Coding problem4

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.

1. Counting Sort

Easy

0/40

Asked in companies

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}.

Problem approach

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.

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2. 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?

Problem approach

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.

3. 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.

Problem approach

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.

4. 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?

Problem approach

Tip 1: Be Honest with your answers.