How to Ace Technical Interviews: Insights from an Interviewer

I've been interviewing candidates for SWE roles, and I keep noticing talented individuals making the same common mistakes. Many candidates have strong technical knowledge, but make same mistakes, a few tweaks in their approach could significantly improve their chances. Here’s a guide to help you ace the four main areas of technical interviews: Coding, Object-Oriented Programming (OOP), System Design, and the often underestimated Competency.

General Advice for All Interview Types Listen carefully. Each interview has unique expectations, so begin by listening attentively to the interviewer’s framing of the problem and ask clarifying questions if needed. Show them you’re interested in understanding the problem deeply before jumping in.

1. Coding

When it comes to coding interviews, one of the biggest pitfalls I see is rushing to a solution. Many candidates see a familiar pattern and immediately start coding. Remember, we’re not only evaluating your coding skills but also your ability to apply critical thinking and problem-solving effectively.

• Read the problem carefully. Take a moment to truly understand the question. Even if it resembles a problem you've solved before, treat it as new. We want to see your unique approach to solving it not your memory of remembering the answer.
• Ask questions if anything is unclear. Clarifying even small details shows thoughtfulness and a careful approach, two qualities that are highly valued.
• Break down your solution. Explain your thought process step-by-step, outlining why you’re choosing specific data structures or algorithms. This shows the interviewer that you’re thoughtful in your choices and capable of adapting to different challenges.
• Write clean, readable code. Optimize for readability rather than cleverness. Choose variable names that convey meaning, avoid shortcuts, and always structure your code logically.
• Think out loud. Explaining decisions like why you’re using a particular loop or why you picked a certain data structure gives the interviewer insight into your critical thinking. Highlight any potential edge cases you’re accounting for to show that you’re thorough.

2. Object-Oriented Programming (OOP)

OOP interviews go beyond algorithmic skill. They test your ability to structure and design code that reflects real-world scenarios and scalable software design.

• Focus on understanding the requirements. A common mistake is rushing to write code without understanding the full problem. Instead, start by defining what the requirements entail and which design principles best align with them. Ask questions like, "What’s the expected scale?".
• Plan a high-level design. Before writing a single line of code, structure your approach. Map out the core components, define their relationships, and choose an appropriate design pattern that fits the problem well.
• Implement with a modular approach. After planning, write each class one by one, focusing on maintaining encapsulation and clarity. Describe each component as you go, explaining how they fit together. This demonstrates a project-focused mindset and an understanding of real-world applications.
• Explain your choices. Good OOP isn’t just about functionality but also about maintainability and scalability. Explain why you’re structuring your classes in a particular way and how it will help maintain or extend the codebase in the future. Use different OOP concepts and explain it while writing the code.

3. System Design

System design is often challenging, even for experienced professionals. It’s less about getting the "right" answer and more about showing a structured approach to designing complex systems.

• Clarify the requirements. System design questions are usually broad to test your analytical skills, so start by asking questions to narrow down the scope. For example, "Is this intended for a global user base?" or "Do we need to prioritize scalability over cost-efficiency?" Gather all relevant requirements before diving into the design.
• Sketch a high-level design first. Use a whiteboard or a visual tool to outline the major components and interactions. This could include the database, APIs, load balancers, caching layers, and any other critical infrastructure. Starting simple allows you to see the big picture before getting into the specifics.
• Focus on critical parts. Rather than explaining every single component in detail, choose one or two key areas and dive deeper. For example, if you’re designing a movie ticket booking system, explain the ticket-locking mechanism and queue management in depth. Describe how you would handle concurrent requests and large user volumes.
• Discuss scalability and trade-offs. System design is often about choosing between different approaches, each with pros and cons. Show the interviewer that you understand how various choices impact performance, scalability, and maintainability. For example, discuss whether to use horizontal vs. vertical scaling or whether to implement sharding in your database.
• Explain your API and database structure. Go into detail about how you would structure the database for fast access and low latency. Specify how different components interact and justify your design decisions.

4. Competency (Soft Skills & Team Fit)

While technical skills are crucial, many candidates overlook competency-based questions that gauge teamwork, adaptability, and problem-solving under pressure. These are essential to showing that you’re a well-rounded candidate who will fit in well with the team. Use the STAR method (Situation, Task, Action, Result) to give structured, impactful answers.

• Emphasize collaboration. Be ready to discuss how you work in teams, handle constructive feedback, and manage differences of opinion. Microsoft values people who can communicate effectively and contribute to a positive team environment.
• Showcase problem-solving skills. Think of examples where you encountered a challenge and successfully navigated it. Demonstrating how you approach roadblocks, whether technical or interpersonal, can set you apart.
• Highlight adaptability. In a fast-paced environment, flexibility is key. Talk about instances where you had to adjust to new tools, requirements, or processes and how you handled it effectively.

Closing Thoughts

Remember, interviews are as much about communication and collaboration as they are about technical know-how. By listening actively, explaining your thought process, and approaching each part of the interview with clarity, you’ll not only demonstrate your technical expertise but also your readiness to succeed in a collaborative work environment.

Good luck—and keep growing!