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Technical Interview Prep

Process over solution. How to communicate your thinking and demonstrate real engineering depth.

The Three Pillars of Technical Interviews

Most technical interview loops test these three areas. Prepare for all of them.

Coding Round

Data structures, algorithms, problem decomposition. Think out loud.

System Design

Architecture, trade-offs, scalability. Senior+ focus. Show you can think at scale.

Behavioral

Past experiences, conflict resolution, leadership. Use STAR method.

The Coding Round

The goal isn't just to solve the problem—it's to show how you think. Interviewers are evaluating your problem-solving process, not just the final answer.

The 4-Step Framework

Clarify Requirements (2-3 min)

Ask questions. Don't assume. "What's the input size?" "Can there be duplicates?" "Should I optimize for time or space?" This shows you think before you code.

Talk Through Your Approach (3-5 min)

Before writing code, explain your plan. "I'm thinking of using a hash map to track frequencies, then..." Get feedback before investing time in the wrong direction.

Code While Explaining (15-20 min)

Write clean, readable code. Use meaningful variable names. Keep talking: "Now I'm iterating through the array to find..." Silence makes interviewers nervous.

Test Edge Cases (5 min)

Walk through your code with examples. "What if the array is empty? What if all elements are the same?" Finding your own bugs is a strong signal.

Patterns Worth Knowing

You don't need to grind 500 LeetCode problems. Master these patterns and you'll recognize most interview problems:

Two Pointers / Sliding Window

Hash Maps for O(1) Lookups

BFS / DFS (Trees & Graphs)

Binary Search

Dynamic Programming (Start with Memoization)

Stacks / Queues / Heaps

System Design (Senior+)

System design interviews test your ability to think at scale and make trade-offs. There's no "right" answer—they want to see your reasoning process.

Deep Dive: System Design Interviews 2025 - What's Changed

The System Design Framework

Requirements Gathering (5 min)

Functional: What should the system do? Core features only.
Non-functional: Scale (users, QPS), latency, availability, consistency requirements.

High-Level Design (10 min)

Draw the big boxes: clients, load balancers, app servers, databases, caches. Show the data flow. Keep it simple first.

Deep Dive (15-20 min)

Pick 2-3 components and go deep. DB schema, API design, caching strategy. This is where you show expertise. Let the interviewer guide you.

Bottlenecks & Trade-offs (5-10 min)

What are the weak points? How would you scale? What did you trade off? "We chose eventual consistency for availability, but that means..."

Key Concepts to Know

Scaling

Horizontal vs vertical, load balancing, database sharding, read replicas

Caching

Redis/Memcached, cache invalidation strategies, CDNs, cache-aside vs write-through

Databases

SQL vs NoSQL trade-offs, ACID, CAP theorem, indexing strategies

Async Processing

Message queues (Kafka, RabbitMQ), event-driven architecture, pub/sub

The Behavioral Round

Behavioral interviews aren't about having "perfect" answers. They're about showing self-awareness, growth, and how you work with others. Use the STAR method to structure your responses.

The STAR Method

Situation

Set the context. "At my last company, we had a legacy system that was causing 3+ hours of downtime per month..."

Task

What was your responsibility? "I was asked to lead the migration to a new architecture..."

Action

What did YOU do? Be specific. "I proposed a strangler fig pattern, created the RFC, and led a 3-person team..."

Result

What was the outcome? Use metrics. "Reduced downtime to under 15 minutes/month and saved $200K in ops costs."

Prepare Stories For These Themes

Technical Leadership: "Tell me about a time you drove a technical decision."

Conflict Resolution: "Describe a disagreement with a teammate and how you resolved it."

Failure & Learning: "Tell me about a project that didn't go as planned."

Ambiguity: "How do you approach problems without clear requirements?"

Impact: "What's the most impactful project you've worked on?"

Culture Add, Not Culture Fit

Great teams don't hire clones. When asked about culture, think about what unique perspective you bring. What gaps can you fill? How do you raise the bar? "I noticed the team was strong in backend but needed frontend architecture expertise—that's where I can add value."

Quick Tips

Think Out Loud

Silence is your enemy. Share your thought process even when stuck.

Ask for Hints

If stuck, ask. "I'm considering X approach—does that seem reasonable?"

Start Simple

Get a brute force solution first. Optimize later. A working solution beats a perfect attempt.

Prepare Questions

Have 3-5 thoughtful questions ready. "What does success look like in the first 90 days?"

Frequently Asked Questions

Which programming language should I use for interviews?

Use the language you are most comfortable with. Interviewers care about your problem-solving ability, not syntax trivia. Python is popular for its brevity, but Java, C++, or C# are perfectly fine if that's your strength.

How many LeetCode problems do I need to solve?

It's not about the number, but the patterns. Focus on understanding the underlying patterns (Sliding Window, DFS/BFS, Dynamic Programming) rather than memorizing hundreds of solutions. Solving 50-75 diverse problems well is better than 300 poorly.

How do I handle getting rejected?

Rejection is a normal part of the process, even for the best engineers. Treat every interview as a data point. Ask for feedback if possible, reflect on what went well and what didn't, and use it to refine your preparation for the next one.

What if I get stuck during the coding interview?

Communicate! Explain your thought process, what you are trying to achieve, and where you are blocked. Interviewers often give hints if they see you are thinking in the right direction. Silence is your worst enemy.

Ready to put this into practice?

When you work with OneCube, we prep you for each interview. You'll know the format, the interviewers, and what to expect—no surprises.

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