How to Crack Technical Interviews at TCS, Infosys & Wipro

Understanding the Selection Process

India's top IT companies follow a broadly similar selection pattern, though each has its own difficulty and format.

TCS NQT (National Qualifier Test)

TCS uses the NQT as its primary selection tool. It has three sections: Cognitive Skills (numerical ability, verbal, reasoning — 40 questions in 40 minutes), Programming Concepts (DSA, algorithms, output-based MCQs — 25 questions in 25 minutes), and Advanced Coding (2 live coding problems in C/C++/Java/Python — 45 minutes). A strong NQT score also opens doors to TCS partner companies in the NQT ecosystem.

Infosys (InfyTQ + Campus Drive)

Infosys hires through campus drives and InfyTQ certification. The process includes an online assessment covering aptitude, reasoning, and English, followed by a technical interview and HR round for shortlisted candidates. Infosys emphasises data structures and communication skills.

Wipro (WILP / National Talent Hunt)

Wipro's process includes an aptitude test, a written communication assessment (an essay on a given topic), a technical interview, and an HR interview. Wipro values learning agility — the ability to pick up new technologies quickly.

Phase 1: Aptitude Preparation (4–6 Weeks)

The aptitude test eliminates the largest number of candidates. This is entirely learnable with consistent daily practice.

Quantitative Aptitude Topics

• Number systems, HCF, LCM
• Percentages, profit and loss, discount
• Time and work, time-speed-distance
• Simple and compound interest
• Permutations, combinations, probability
• Data interpretation — tables, bar graphs, pie charts

Resources: R.S. Aggarwal's Quantitative Aptitude for theory. IndiaBix.com and PrepInsta.com for company-specific practice.

Verbal and Logical Reasoning

Verbal sections test reading comprehension, fill-in-the-blanks, and vocabulary. Read a reputable English newspaper for 20 minutes daily to naturally build these skills. For logical reasoning, practice series completion, syllogisms, blood relations, seating arrangements, and coding-decoding puzzles.

Phase 2: Core CS Concepts (3–4 Weeks)

Technical interviews at all three companies test Computer Science fundamentals. Even if you specialise in one language, you may be asked OS or DBMS questions.

Data Structures and Algorithms

This is the single most important area. Master: arrays and strings, linked lists (singly, doubly, circular), stacks and queues, binary trees and BSTs, hash maps, sorting algorithms with time/space complexity, and basic graph theory (BFS, DFS). Practice at least 30–40 problems on LeetCode (Easy to Medium) or HackerRank. For TCS specifically, solve previous-year NQT coding questions on PrepInsta.

Object-Oriented Programming

Every IT interview asks OOP questions. Know the four pillars deeply: encapsulation, inheritance, polymorphism, abstraction. Understand abstract class vs. interface, method overloading vs. overriding, constructors, and access modifiers. Be ready to write small code snippets live.

Database Management and SQL

Write SQL queries confidently: SELECT with WHERE, GROUP BY, ORDER BY, HAVING. Understand all JOIN types. Know DELETE vs. TRUNCATE vs. DROP. Explain normalisation up to 3NF and ACID properties with examples.

Operating Systems and Computer Networks

For OS: process vs. thread, deadlock conditions, CPU scheduling algorithms (FCFS, SJF, Round Robin), paging and segmentation. For CN: OSI model layers and functions, TCP vs. UDP, DNS, HTTP/HTTPS, and be able to explain what happens when you type a URL in a browser.

Phase 3: Coding Round Strategy

• Start with Easy problems on LeetCode before attempting Medium. Do not jump to Hard until Easy problems are consistently solvable.
• Learn patterns: sliding window, two pointers, BFS/DFS, dynamic programming basics, binary search — most problems are variations of these.
• Write clean code: meaningful variable names, brief comments, always consider edge cases (empty array, single element, negatives).
• Simulate exam conditions: use a plain text editor (no IDE autocomplete) and a 45-minute timer for two problems.

Phase 4: Technical Interview Preparation

Once you clear the online test, prepare for the face-to-face or virtual technical round:

Know Your Resume Cold

Every technology listed is fair game. If you wrote "Spring Boot," expect dependency injection questions. If you listed "MySQL," expect to write SQL queries live. Remove anything from your resume you cannot confidently explain.

Project Explanations

For every project, be ready to explain: the problem it solves, the tech stack and why you chose it, the specific challenges you overcame, how you tested it, and what you would improve with more time. Practise explaining this in under 3 minutes.

8-Week Study Plan

• Weeks 1–2: Aptitude — quantitative topics, 2 hours/day
• Weeks 3–4: Verbal/logical reasoning + OOP fundamentals
• Weeks 5–6: Data structures + SQL + 20 LeetCode Easy problems
• Week 7: OS and CN basics + 15 LeetCode Medium + full mock tests
• Week 8: Mock interviews, project deep-dives, company-specific papers

Best Free Resources

• Aptitude: IndiaBix, PrepInsta, R.S. Aggarwal
• Coding: LeetCode Easy/Medium, HackerRank, GeeksForGeeks
• Core CS: GeeksForGeeks, NPTEL video lectures
• Company-specific: PrepInsta company-wise papers, TCS iON practice tests