[CS Technical Interview 5] Data Structures That Make Sense

💬 Getting a developer job - coding tests weren't the end of it.

As someone from a non-computer science background, I initially focused only on algorithms and coding tests when preparing for my first developer job. I gained confidence and passed most coding tests. However, I kept failing at the next hurdle - technical interviews.
What was the problem? It was the lack of CS (Computer Science) knowledge. In interviews, CS fundamentals were considered much more important than algorithms.

🗣 For actual interviews, 'speaking practice' was important.

Even after filling in my CS fundamentals, interviews weren't easy. At a certain company's interview, I was asked about floating-point numbers. It was content I had definitely read multiple times in books and thought I understood, but I couldn't utter a single word. I painfully realized that passive learning through simply reading and understanding wasn't enough to answer questions in real interviews.

To succeed in interviews, you need not only to accumulate a lot of knowledge but also the ability to explain this knowledge. This 'ability to explain' can only be developed through practice of organizing concepts into just a few sentences and speaking them out loud. Through this process, you can also discover what you didn't know precisely. Without sufficient practice, you'll encounter the following problems.

1. Conceptual Confusion Type

❓InterviewerWhat are the characteristics of object-oriented programming?
💬 Candidate The SOLID principles. First, S is..(omitted)...

This is a case of confusing similar concepts.
SOLID is an OOP design principle, while the characteristics of object-oriented programming are abstraction, encapsulation, inheritance, and polymorphism.
The moment you mix up related concepts, the interviewer judges that 'your fundamentals are shaky'.
It's not just a simple mistake, but rather it's read as a signal that your conceptual framework is not solidly established.

2. Lack of Specificity Type

❓Interviewer What are the characteristics of TCP?
💬 Candidate It's a protocol that guarantees reliability.
❓ Interviewer What are the mechanisms that guarantee reliability?
💬 Candidate Uh... well... it makes transmission secure... like that...

This is a case where you only know the What, but are missing the How/Why.
You only know the superficial answers and aren't prepared to explain the underlying principles.
TCP establishes communication through connection (3-way handshake), ensures reliability through RDT (sequence numbers, ACK, retransmission, etc.), and maintains quality through flow control and congestion control.
These concepts should be connected as one coherent flow in your mind. Without organizing concepts concretely, you cannot prepare for follow-up questions.

3. Getting tongue-tied with basic questions

❓Interviewer What is HTTP?
💬 Candidate Um... it's for sending and receiving data on the web... something like that...?

It's such a familiar concept, but when asked to explain it in one sentence, the words don't come easily.
Words like request, response, server, and client come to mind, but they don't flow naturally into a coherent sentence.
This is because we've never practiced explaining from definition to principles in one continuous flow.
This isn't a lack of knowledge, but an absence of structure.

Just knowing is not enough. It only becomes true skill when you can express it in words.

🔥 That's why I created it. The CS Technical Interview Series That Gets You Talking!

🎯 Recommended for these people

⚡ Lecture Core Kick

💡 Use it like this

💬 Q. The lecture time is short, but will I be able to learn properly?

🖐 Hello! Let me introduce myself! 🙇

I created this course thinking of my past self, who stayed up all night worrying about fundamentals and felt anxious over every single interview question.

I started as a non-CS major and understand better than anyone the thirst for fundamentals (CS knowledge, programming languages, etc.). Through self-studying countless materials and building my own know-how, I eventually graduated from Seoul National University and now work as a 🧑🏻‍💻 Kakao developer.

Since childhood, I've been more confident than anyone in combining and reconstructing various materials to create 'my own consolidated study notes.' This course is precisely that secret notebook born from my 'ultimate self-study know-how' and all my passion and philosophy.

🔥 What makes this course special?

• All of my 'know-how' is included: As a non-CS major, I have fully incorporated my experience and know-how of self-studying CS and programming languages and getting hired at a large corporation. I have included in this course all the methods for how to most efficiently understand complex and abstract concepts and make them your own.

• 'Fundamentals' are key in any development field: Whether you're aiming for game development, AI, web/app development, or any other field, basic computer science knowledge is not optional but essential. This course helps you become a true expert based on solid fundamentals.

• We compete with 'overwhelming quality': I've referenced countless materials including textbooks, famous university lectures, commercial books, and technical interview resources to extract core keywords and reconstruct them in my own unique way. With intuitive diagrams and illustrations, combined with easy explanations infused with my practical experience, I promise to make even complex concepts click with that "Ah, now I get it!" moment.

🚀 Introducing the fifth lecture [Data Structures] from the Technical Interview Master Roadmap.

📕 Data Structures, 'When to Use What?' Develop That Intuition!

Data structures go beyond simply knowing the concepts,

• Still confused about when to use stacks and queues❓

• Are you feeling overwhelmed about how complex data structures like trees or graphs are actually applied to real-world problems❓

In other words, it's a subject where you need to develop intuition about "when and which structure is best to use?" However, for beginners, various structures are scattered in fragments, and it often causes frustration because they can't get a sense of where and how stacks/queues/trees/graphs are used.

This course is designed specifically for those people, delivering the core concepts of each data structure intuitively through diagram-centered visualization, and clearly comparing the advantages, disadvantages, and selection criteria for each structure so you can easily understand and remember them for a long time. I strongly recommend this course to those who have done basic coding but found data structures overwhelming, and to those who want to organize CS theory.

🎯 Through this course, you will be able to clearly answer the following questions.

How are arrays and linked lists structurally different, and what situations are each suitable for?
→ We'll visually explain the core concepts focusing on the differences in memory layout, access methods, and insertion/deletion operations.

How do stacks and queues process data according to what rules?
→ We organize the LIFO and FIFO principles with diagrams and examples, and also convey their practical application contexts.

What are the structural differences between trees and graphs?
→ We've structured the content to help you clearly distinguish and understand essential concepts such as hierarchical structure, presence of cycles, and traversal methods.

When is a heap useful?
→ We systematically explain the operating principles of heaps through priority queues and the principles and implementation methods of min/max heaps.
→ We also cover practical use cases such as sorting and scheduling.

📌 At the end of the lecture, a practical interview practice chapter awaits you.

"What is the difference between arrays and lists?", "What are the conditions for a good hash function?",
"What is a heap data structure?" and other
training to organize and articulate answers to frequently asked technical interview questions can be practiced.

📖 A curriculum packed with only the essentials

This is the table of contents and key keywords you will learn in this course.

If there are any unfamiliar keywords, make sure to grasp them thoroughly this time.

✏ Here's what you'll learn

👀 Course Preview

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💡 Curious about other interview preparation courses? Check out the roadmap below :)

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