Complete Coding Interview Preparation Guide for IT Jobs 2026

Cracking a coding interview is a skill — separate from being a good programmer. Here's the complete strategy to prepare for every stage of tech interviews in India.

Understanding the Tech Interview Structure

Most IT companies follow this structure:

Round 1: Online Aptitude

Already covered in detail in our aptitude guide. Key: practice 30+ questions daily for 3 weeks.

Round 2: Coding (The Most Important Round)

Topics by Priority

High Priority (must master):

• Arrays and Strings: sliding window, two pointers
• Linked Lists: reversal, cycle detection, merging
• Stacks and Queues: monotonic stack, sliding window max
• Trees: BFS, DFS, binary search trees
• Hashing: frequency counting, two-sum patterns

Medium Priority:

• Dynamic Programming: memoization, tabulation
• Binary Search: search in rotated arrays
• Graphs: BFS, DFS, topological sort

Lower Priority (FAANG and competitive):

• Segment trees, tries, advanced graphs

The Problem-Solving Framework (STAR-C)

When given a coding problem:

1. S - Summarize: repeat the problem in your own words
2. T - Test cases: write 2–3 test cases including edge cases
3. A - Approach: explain your approach before coding
4. R - Run: code it, dry-run with your test cases
5. C - Complexity: state time and space complexity

This framework shows interviewers your thought process — which matters as much as the solution.

LeetCode Plan by Company

Round 3: Technical Interview 1

CS Fundamentals Questions (Most Common)

DBMS:

• What is normalization? Explain 1NF, 2NF, 3NF
• What is indexing? Types of indexes?
• ACID properties in databases

OS:

• What is a process vs thread?
• What is deadlock? Conditions?
• Virtual memory and paging

Networks:

• What happens when you type google.com?
• TCP vs UDP differences
• HTTP vs HTTPS

OOP (Java/Python):

• 4 pillars of OOP with examples
• Abstract class vs Interface
• Method overriding vs overloading

Programming Language Questions

Java: Collections framework, garbage collection, multithreading basics
Python: List vs tuple vs set, decorators, generators

Round 4: System Design (For Senior Roles)

For freshers, system design is rarely tested deeply. For roles targeting 3+ years experience:

• Design a URL shortener (like bit.ly)
• Design a messaging system
• Design a parking lot

Key concepts: scalability, caching, databases, load balancing.

Round 5: HR Interview

Most common behavioral questions:

1. "Tell me about yourself" — 90-second pitch
2. "Why this company?" — research required
3. "Tell me about a challenge you overcame" — STAR method
4. "Where do you see yourself in 5 years?" — show ambition + realism
5. "Do you have any questions for me?" — always say yes

90-Day Interview Preparation Plan

Classroom Tech Interview Support

Classroom Tech runs dedicated placement preparation:

• DSA coaching with Satyaki Das
• Mock coding interviews (timed, real conditions)
• CS fundamentals review
• HR interview practice

Satyaki Das (TCS employee and GATE-qualified) provides insider coaching on exactly what TCS and similar companies look for.

Book a preparation session at Topmate.

About Satyaki Das & Classroom Tech

Satyaki Das is the Founder of Classroom Tech and Co-Founder of XShare. He holds an MTech in Computer Engineering from Jadavpur University and an MCA from Techno Main, Salt Lake, Kolkata. A Java Full Stack Developer at TCS, GATE-qualified, and Codevita Rank 848, Satyaki has 11+ years of teaching experience mentoring BCA, B.Tech, MCA, and working professionals into roles at TCS, Wipro, Infosys, Accenture, EY, Deloitte, and Capgemini.

📍 Kolkata, West Bengal, India | 11k+ LinkedIn Followers
🔗 LinkedIn | 💻 code.classroomtech.in | 📘 classroomtech.in
🗓️ Book 1:1 on Topmate | 📞 8981838547