How to prepare for coding interviews and campus placements: a 90-day plan
By Vikram · Updated 26 Oct 2026
Most coding interviews and campus placements test the same five things: data structures and algorithms (DSA), one programming language in depth, SQL, core computer science and the projects on your resume. Ninety days of steady, daily practice is enough to get interview-ready if you spend them on the right things in the right order.
What placement and coding interviews test
| Round | What it checks | How to prepare |
|---|---|---|
| Online assessment (OA) | MCQs on aptitude, CS fundamentals and output questions, plus 2–3 coding problems | Timed MCQ practice and easy-to-medium coding problems |
| Technical interview 1 | DSA problem solving, thinking aloud, complexity | Problem patterns, not memorised solutions |
| Technical interview 2 | Projects, OOP, DBMS, OS, networks, SQL | Know every line of your resume; revise core subjects |
| HR / managerial | Communication, teamwork, motivation | Stories from projects and hackathons |
The 90-day plan
Days 1–30: foundations
- Pick one language (Python, Java or C++) and learn its standard library: lists, maps, sets, heaps, sorting.
- Cover arrays, strings, hashing, two pointers, sliding window, stacks and queues. Solve 2–3 easy problems a day.
- Learn time and space complexity properly: you will be asked for it on every problem.
- Start SQL: SELECT, WHERE, GROUP BY, HAVING and the four kinds of JOIN. See SQL interview questions.
Days 31–60: core DSA patterns
- Linked lists, binary search, recursion and backtracking, trees and binary search trees, heaps.
- Graphs: BFS, DFS, topological sort, shortest paths. Then dynamic programming, starting from 1-D problems.
- Move to medium problems. After each one, write down the pattern it used. See DSA interview questions and patterns.
- Revise DBMS (normalisation, indexes, transactions), OS (processes, threads, deadlocks, paging) and OOP.
Days 61–90: interview mode
- Timed practice: two problems in 45 minutes, explaining your approach out loud.
- Mock interviews with friends; swap interviewer and candidate.
- Polish two strong projects. A hackathon project with a live demo is one of the best things to talk about.
- Revise your notes of patterns and mistakes every weekend.
A daily routine that works
- 10 minutes: a quick quiz to warm up. The Hack4Hack Daily Quiz gives 10 timed MCQs on DSA, Python, SQL, ML and AI every day at 4 PM IST.
- 60–90 minutes: 2 coding problems on today's topic.
- 20 minutes: one core CS or SQL topic.
- 10 minutes: update your mistake log.
Tip: Consistency beats intensity. An hour and a half every day for 90 days is worth more than a few 10-hour weekends. Streaks help: keep yours going on the Daily Quiz leaderboard.
Projects and hackathons
Interviewers spend a lot of time on your projects. Two complete projects that you can explain end to end, the design choices, the trade-offs, what broke and how you fixed it, beat five tutorial clones. Hackathons give you a deadline, a team and a real problem: find one on the hackathons page, or read how to win a hackathon.
Frequently asked questions
How many DSA problems should I solve for placements?
Quality matters more than the count. Around 150–250 well-chosen problems that cover every major pattern, solved and revised properly, is enough for most placement interviews.
Which language is best for coding interviews?
The one you know best. Python is quick to write, Java and C++ are common in placements. Interviewers care about your logic and complexity, not the language.
Is 3 months enough to prepare for placements?
Yes, for most students, with 1.5–2 hours of focused practice every day: a month of foundations, a month of DSA patterns and a month of timed, interview-style practice.
Do hackathons help in placements?
Yes. A hackathon project gives you a real product to discuss, proof of teamwork under a deadline and often a prize or certificate for your resume. Some hackathons are run by companies to hire directly.