Software Engineer Interview Questions With Worked Answers

Last updated: 21 September 2026 · By the Asuraa Team

What are the most common software engineer interview questions?

Software engineer interview questions usually fall into coding, system design and behavioural rounds. Tech Interview Handbook's interview guide, updated 7 August 2026, names these three and notes that earlier stages can include quizzes, online coding assessments, take-home assignments and phone screens.

The table pairs each group with what it tests and example questions. The examples come from DataCamp's software engineer question list (15 June 2025), and the notes on what each tests are ours.

The DataCamp list labels some questions as advanced for senior candidates, so read each question against your own level.

How do you answer a coding question? (a worked example)

Restate the problem, give a simple solution first, then improve it and explain why. Take the classic two-sum question: given a list of numbers and a target, return the positions of two numbers that add up to the target. This is an illustration we tested in Python.

The simple approach checks every pair, which takes time proportional to the square of the list length. A better approach stores each number in a dictionary as you go and looks for the number you still need.

def two_sum(nums, target):
    seen = {}                      # number -> index
    for i, n in enumerate(nums):
        need = target - n
        if need in seen:
            return [seen[need], i]
        seen[n] = i
    return []                      # no pair found

print(two_sum([2, 7, 11, 15], 9))   # [0, 1]
print(two_sum([3, 3], 6))           # [0, 1]
print(two_sum([1, 2], 10))          # []

Why is the dictionary version faster? The Python wiki's time complexity table lists dictionary get and set as O(1) on average, and checking membership in a list as O(n). That means each loop step is cheap on average, so the whole function makes a single pass.

Say these things aloud: the duplicate case ([3, 3]), the case with no answer, and that the worst case for a dictionary is slower than the average. Mentioning the trade-off, more memory for less time, shows you understand the choice.

How do you answer basic computer science questions?

Give a one-line definition, then a short example or trade-off. Take the question "why is checking whether an item is in a set faster than checking a list?" A model answer runs in three sentences.

"A list has to check items one by one, so membership takes time proportional to its length. A set uses hashing, and the Python wiki lists membership as O(1) on average. The trade-off is that a set holds unique items without order and uses extra memory."

Practise the same pattern for the DataCamp basics such as Big O and the four pillars of object-oriented programming. Use your own project as the example where you can, because a real example is harder to fake.

What system design basics should a fresher know?

Learn the vocabulary and a four-step approach, and keep expectations modest. Tech Interview Handbook describes system design as a round for mid and senior levels, so as we read it, freshers are less likely to face a full design round. Some employers may still ask a simple design question, so the basics are worth an evening or two.

The System Design Primer on GitHub suggests four steps: outline use cases, constraints and assumptions; sketch a high-level design; design the core components; then scale the design. It defines a load balancer as something that spreads incoming requests across resources, and a cache, such as Memcached or Redis, as an in-memory key-value store that speeds up access to frequently used data.

Here is an illustration for a URL shortener, using those four steps.

1. Use cases and constraints. Users paste a long link and get a short one, and opening the short link redirects. Ask how many links, how many redirects per second and whether links expire.
2. High-level design. A web service takes the long link, stores a mapping in a database and returns a short code.
3. Core components. Choose how to generate short codes without clashes, and design a table of code to long link.
4. Scale. Redirects usually outnumber creations, so add a cache for popular links and a load balancer across several servers.

Practise saying each step in one or two sentences. Your goal is a clear structure, not a perfect architecture.

How do you answer behavioural questions?

Use the STAR method and a story from your own work. Tech Interview Handbook's guide names STAR (situation, task, action, results) as the format to master and to practise the common software engineering behavioural questions.

Here is an invented illustration for the question "tell me about a disagreement in a team". In a final-year project, two teammates wanted different databases (situation), and I had to help the team choose in one week (task).

I listed the requirements, compared the options against them, and we tested both with sample data (action). We picked the one that met the requirements and finished on time, and I learnt to settle disagreements with a small test (result).

Prepare three or four such stories, drawn from projects, internships, hackathons or coursework. Our guide to behavioural interview questions and the STAR method goes deeper.

How should you prepare, step by step?

Start with coding, add basics, then practise speaking. Tech Interview Handbook suggests about three months at around 11 hours a week for coding interview preparation, as a general guide and not a promise.

1. Pick one language. Use the one you know best.
2. Practise patterns. Work through arrays, strings, hash maps, linked lists, trees and sorting, and study the pattern behind each solution instead of memorising it.
3. Time yourself. Solve problems within a set limit and explain aloud.
4. Review the basics. Big O, object-oriented programming, databases and your own project's design.
5. Learn the design vocabulary. Load balancer, cache, database and API, using the four steps above.
6. Write your stories. Three or four STAR stories, practised aloud.

Our software engineer roadmap for India shows where interview practice fits, and the technical interview questions post covers general preparation.

What if you do not know the answer?

Say what you do know, think aloud, and ask a clarifying question. Interviewers often care about how you reason, and a calm attempt with a stated assumption is better than silence.

If you get stuck on code, start with the simplest version that works, even if it is slow, and improve it. Say what you would check next. That approach also gives you something to submit if time runs out.

What do most guides on software engineer interview questions get wrong?

Many guides are long lists with model answers to memorise. These are the gaps.

• They skip the reasoning. A memorised answer falls apart when the interviewer changes one detail.
• They treat every round as equal for freshers. Sources describe system design as a mid and senior round, so time spent on it should follow your level.
• They ignore behavioural rounds. Tech Interview Handbook lists them as a full round, and a fresher with no job history needs stories from projects.
• They present one company's process as universal. We do not describe any company's real process, and you should check candidate reports for your target employers.

FAQ

What are the most common software engineer interview questions for freshers?

Freshers mostly see coding questions on data structures and algorithms, basics such as Big O and object-oriented programming, and behavioural questions about projects and teamwork. DataCamp's list includes reversing a linked list and comparing DFS and BFS. Check your target employers' formats.

How do I prepare for software engineer interview questions in a month?

Focus on one language, core data structures such as arrays, strings and hash maps, and two or three STAR stories. Tech Interview Handbook suggests about three months at 11 hours a week for coding preparation, so a month means narrowing scope to the basics.

Do freshers get system design questions?

Sometimes, but less often. Tech Interview Handbook describes system design as a round for mid and senior levels. Freshers should still know terms such as load balancer and cache, and how to walk through requirements, high-level design, components and scaling.

How should I answer behavioural questions in a software engineer interview?

Use STAR: situation, task, action and result. Tech Interview Handbook names it as the format to master. Prepare three or four stories from projects, internships or teamwork, and practise them aloud so they stay specific and short.

Is DSA enough to clear a software engineer interview?

Not always. Coding is one round, and sources also describe behavioural and, for more senior levels, system design rounds. Practise patterns, explain your reasoning aloud, and prepare stories about your projects.

What should I do if I get stuck in a coding interview?

Say what you know, state your assumptions and start with the simplest working approach, then improve it. Ask a clarifying question if the problem is unclear. Interviewers often want to see how you reason, so keep talking through your steps.

Final thoughts

Software engineer interview questions reward clear thinking more than memory. Practise patterns, explain aloud, learn the design vocabulary and write your stories.

For the wider process, read how to prepare for a job interview in India, and browse openings on the jobs page.