Coding Adda Docs

A complete, practical guide for CS students to crack placement interviews - DSA, projects, system design, HR rounds, mistakes and prep strategy.

Introduction: Placements Aren't about being the Smartest - They're about being Prepared

Every year, thousands of Computer Science students walk into placement interviews thinking, "I know coding, I should be fine." And every year, most of them walk out confused about why they didn't clear it. Here's the uncomfortable truth: placements reward structure preparation, not raw intelligence. Companies don't hire the student who knows everything. They hire the one who can:

Think clearly under pressure
Explain trade-offs
Write readable code
Communicate like an engineer, not a tutorial-watcher This guide breaks the illusion and gives you a battle-tested, step-by-step roadmap to prepare for placement interviews as a CS student - whether you're in 2nd year planning early or in final year with deadlines breathing down your neck.

1. Understand the Placement Interview Landscape

Before preparing, you must understand what you're preparing for. Most tech companies (product + service) follows this structure:

Online Assessment (OA)
- DSA Problems
- MCQ (OS, DBMS, CN, OOPs)
Technical Interviews
- Coding + Problem Solving
- Core CS Fundamentals
- Projects discussion
System Design / Machine Coding (for mid/high packages)
HR/Managerial Round Many students fail because they over-prepare one round and ignore others.

2. Data Structures & Algorithms: How Much is Actually Enough ?

You do NOT need to solve 1000 LeetCode problems. You need depth, patterns, and explanation clarity.

What Interviewers Actually Look For

Can you identify the right data structure ?
Can you explain your approach before coding ?
Can you handle edge cases ?
Can you optimize when asked ?

Core DSA Topics You Must Master

Arrays & Strings
Hashing
Stacks & Queues
Linked Lists
Recursion & Backtracking
Trees & BST
Heaps
Graphs (BFS,DFS)
Greedy Algorithms
Dynamic Programming (basic to medium)

Practical Strategy (This Works)

Pick one language
Solve 150-200 quality problems, not random ones
After every problem, ask:
- Why this approach ?
- What's the time & space complexity ?
- What breaks if constraints increase ?

3. Core CS Subjects

You might clear DSA and still get rejected in 10 minutes. Why? Weak fundamentals.

Subjects You Must Prepare

Operating Systems
- Process vs Threads
- Deadlocks
- Scheduling
DBMS
- Normalization
- Indexing
- Joins
- Transactions (ACID)
Computer Networks
- TCP vs UDP
- HTTP vs HTTPS
- DNS
OOPs
- Inheritance
- Polymorphism
- SOLIC principles

How Interviewers Ask

Not definitions. They ask scenarios. For example:

"Why do we need indexing ? When does it fail ?"

Preparation Tip

Explain every concept like you’re teaching a junior.
If you can’t explain it simply—you don’t know it yet.

Projects: Your Strongest Weapon

Projects are like resume-armor.

What Makes a Project Interview-Ready

You built it (not just cloned)
You can explain:
- Architecture
- Tech choices
- Trade-offs
- Failure points
You have users on your project
Your project is live.

Ideal Project Stack

Web app with:
- Frontend (React / Next.js)
- Backend (Node / Spring Boot)
- Database (PostgreSQL / MongoDB)
AI Based app with:
- Clear Problem Statement
- Dataset explaination
- Model choice logic