# Cracking the Technical Interview — Coding Rounds, CS Questions and Projects

Source: https://skills101.in/learn/career/technical-interview-guide — Skills101 free tutorial (Interview & Career). Updated 2026-11-09.

In technical rounds, interviewers judge **how you think**, not only whether your final code runs. A candidate who explains clearly and reaches a decent solution often beats one who silently writes perfect code.

## 1. The 6-step approach to coding questions

![Six steps: understand (restate, ask about input size and edge cases), examples, brute force with its complexity, optimise, code while talking, test with a dry run and edge cases](https://skills101.in/learn-img/career/interview-approach.svg)

### Worked example (spoken aloud)

*"Find two numbers in an array that add up to a target."*

1. **Understand:** "Can there be negative numbers? Exactly one answer? Return indexes or values? How big can the array be?"
2. **Examples:** `[2, 7, 11, 15]`, target 9 → indexes 0 and 1.
3. **Brute force:** "Check every pair — O(n²) time, O(1) space."
4. **Optimise:** "While scanning, store each number in a hash map; for each x, check if target − x is already there — O(n) time, O(n) space."
5. **Code** it, naming variables clearly and explaining each line.
6. **Test:** run the example by hand; then edge cases — empty array, duplicates, no answer.

(Practise this exact problem on our [Two Sum page](https://skills101.in/practice/code/two-sum).)

## 2. What interviewers score

| Area | What they look for |
|---|---|
| Problem solving | asks good questions, finds a working approach, improves it |
| Coding | correct, readable code; handles edge cases |
| Communication | explains thinking; takes hints well |
| CS knowledge | DSA, OOP, DBMS, OS, networks basics |
| Projects | real understanding of what you built |

**Getting stuck is normal.** Say what you're thinking; interviewers often give hints — and using a hint well is a positive sign.

## 3. Talking about your projects

Expect: *"Explain your best project."* Prepare for each project:

- The **problem** it solves and who uses it.
- The **architecture** (draw it: frontend → API → database).
- **Your** part, if it was a team project.
- One **technical challenge** and how you solved it.
- What you'd **improve** with more time (shows maturity).

Interviewers dig into anything on your résumé — if you list Docker, be ready to explain a Dockerfile.

## 4. CS fundamentals: what to revise

| Subject | Must-know topics |
|---|---|
| [DSA](https://skills101.in/learn/dsa) | arrays, strings, hashing, two pointers, recursion, trees, graphs basics, sorting, complexity |
| [OOP](https://skills101.in/learn/oops) | 4 pillars, overloading vs overriding, abstract class vs interface |
| [DBMS & SQL](https://skills101.in/learn/dbms-sql) | keys, normalization, joins, GROUP BY, transactions, indexing, 2nd highest salary query |
| [OS](https://skills101.in/learn/operating-systems) | process vs thread, scheduling, deadlock, paging, virtual memory |
| [Networks](https://skills101.in/learn/computer-networks) | OSI, TCP vs UDP, HTTP vs HTTPS, DNS, what happens when you type a URL |

## 5. Before the interview

- Revise your own résumé — every line.
- Practise 2–3 problems **out loud** with a timer.
- For online rounds: test the coding platform, camera and mic; keep water, paper and a pen.

## Common mistakes

- Jumping into code without clarifying the problem.
- Silence for minutes.
- Not testing your code before saying "done".
- Bluffing — "I don't know, but here's how I'd find out" is far better.

## Quick recap

- 6 steps: understand → examples → brute force → optimise → code → test.
- Think aloud; use hints; mention complexity.
- Know every project deeply; draw its architecture.
- Revise DSA, OOP, DBMS, OS and networks basics.


Practice quiz and free certificate: https://skills101.in/learn/career/technical-interview-guide