38 Companies Passed: Essential Algorithms for 2026 Coding Tests

🎯 A coding test master class perfected through 38 real-world successes

I passed the coding tests for all of the companies below.

Naver, Kakao, LINE, Coupang, Baemin, Karrot, Zigbang, Yanolja, KakaoBank, MyRealTrip, Hyperconnect,

Kakao Mobility, Naver Webtoon, Works Mobile, Banksalad, Ohouse ...

Isn’t that old news? I changed jobs by taking coding tests as recently as last year. I’ve experienced the coding tests currently given by companies. So I know what to prepare and how far to go.

Studying for coding tests without a clear purpose? You no longer need to. I’ll teach you exactly what you need to know to get hired. Learn compactly and pass every coding test.

A collection of real reviews from people who took the course and passed their coding tests.

2025/02/16 Travel Wallet accepted **Mr./Ms. H.

2025/07/31 Final acceptance at 3 companies, Mr./Ms. Oxx

✅ Here's what you'll learn.

Features of this course

📌For complete beginners

• It was created for beginners who have never learned algorithms before.

• We start by explaining why this code is used and how to arrive at that idea, then go into detail about how the values change when the code is actually executed.

• Still, you may not fully understand it, so at the end of the video, I’ve also included a visualization of how the algorithm works.

📌Just diving straight into problem solving?Absolutely not.

• Rather than simply solving problems, I’ll methodically teach you the thought process for how to approach and solve them when you encounter a problem.

• Algorithm problems aren’t designed to be solved only by math geniuses. Brilliant insights? Eureka moments? Absolutely not.

• Each individual element that makes up a problem contains clues about how to solve it. I’ll show you how to pick up those clues.

📌 Community Management

• Nevertheless, you may still have questions or encounter something you don't understand.

• It can naturally happen with online courses.

• So, we’ve created a community where you can ask and answer questions in real time.

• Feel free to join us and ask any questions you have. Also, share algorithm solutions with various developers and try solving them together.

📌 60% theory, 40% practice

• Starting with detailed theoretical explanations and ultimately working through actual problems given by companies, this curriculum covers it all.

Recommended for those who...

🥳🥳🥳 Real Student Reviews 🥳🥳🥳

😨Concern 1😨.
I heard coding test languages are predetermined these days—is that true?

Depending on the stack you’re applying for, I heard the language used for coding tests is predetermined—for example, JavaScript for frontend and Java for backend?

That's right. There are cases where a specific language is required.

I took coding tests at 38 places and encountered this at only two of them.

At almost all the places you apply to, there are generally no restrictions on the programming language.

No matter how you express it, interviewers also know that ultimately, the ability to think through and solve problems is what matters.

😨Concern Point 2😨.
But it’s not my primary language?

You may be worried because it isn’t a language you’ve already learned.

However, I think it is necessary to understand it as easily as possible with Python.

Algorithms are difficult enough already, and when complex syntax is mixed with complicated logic, the code becomes much harder to understand.

When you first study it, it’s best to understand it as easily as possible, and then try expressing it in a more difficult way later.

It’s also a good idea to first understand it through Python and then learn how to express it in your own language.

If you understand the logic using Python, you can definitely express it in Java.

😨Ultimately, a programming language is just a means of expression, and understanding the problem is the most important thing.

And the easiest language to understand and solve problems with is Python.

[Updated July 20, 2025]

We have added supplementary code so that you can also solve the problems in Java and JavaScript, as many students requested!
We have not added explanations in those languages, but we hope you will use this as a good opportunity to review by looking at the same logic implemented in another language!

🎁 EVENT 🎁

There is a special benefit available exclusively to those who take the course.

It contains carefully selected special algorithm problems based on the actual problems encountered while taking 38 real-world coding tests.

Please consider this a spe.cial. problem set created for those who want to study additional problems beyond the theory.
This problem set will be continuously updated, so you’ll be able to prepare for algorithm interviews in line with current trends!!

(This workbook will be provided as a link in the form of a Notion page!)

We will provide this problem set to those who write a course review!

Thank you.

Claim yours after verifying your course review in the algorithm community!

(I’ve explained how to verify it in the very last lecture __)

That's not all.

We’ll also provide a developer job preparation guide (resume, portfolio, and more)!

🎁 EVENT 2 🎁

Through KakaoTalk Plus Friend

🎟 We will send you a discount coupon 🎟
(15% off, cannot be combined with other discounts)

Click the link

🎁 EVENT 3 🎁

Pycharm IDE 3-month free access pass!

In support of your development studies, we have prepared a special benefit through our collaboration with JetBrains.
With the promotion code below, you can use PyCharm for free for three months!

✅ Promotion code: HYUNJOONPARKxJB
✅ Benefit: A 3-month free pass for one JetBrains IDE (e.g., IntelliJ, PyCharm, WebStorm, etc.)
✅ Valid through: December 31, 2026
✅ How to use: 😀

1. Go to the official JetBrains coupon registration page

2. Enter the code, then select your desired IDE

3. Check the license issued via email

⚠ Important notice:
This code is only available to new users who are using JetBrains for the first time.
(Only those who have never used a paid JetBrains license before can register)
(You can create new Google email accounts and do it indefinitely)

😆 Lastly, I’d like to emphasize just two things.

1. This course has undergone two thorough review processes, and all videos include subtitles.

You may think, "Why does that matter?", but many courses are uploaded as-is without being reviewed.

This course underwent two rounds of review to carefully check the subtitles and context, enhancing its overall quality.

2. The textbook has a total of 393 pages.

It was designed so that you can fully understand the content using only the textbook. We have organized and presented the textbook’s content systematically so that you can save your time and learn as efficiently as possible.

2024.11.30 Update

Among the course feedback, there was a comment saying, "It would be nice to have more example problems."

To reflect this, we added bonus problems throughout the lecture materials.

I think you can consider the problems with the 🎆 icon to be bonus problems without separate solution videos.

2024.12.15 Update

Added a link to download the textbook PDF

2025.1.13 Update

3-5. Added an explanation of how to further improve the stack — thanks to zz gg.

1-5. Added an explanation of the criterion for the first non-repeating character in Finding the Mode - thanks to Oh Subin.

3-9. Added an explanation of the condition that, among songs with the same number of plays, songs with lower unique numbers are included first - thanks to sonjs7554.

2025.5.18 Update

4-2 Fixed an animation error in the video - thanks to 애롱님

2025.7.18 Update

3-3 Corrected the selection sort output value error in the textbook - thanks to Yudev

2025.7.20 Update

Added Java and JavaScript problem-solving code

October 15, 2025 Update

Practical Data Structure Library Comparison Table - thanks to BruBru

2025.10.19 Update

Updated boundary value logic and added boundary value tests for Week 4 Homework 1 - thanks to 한달안에 끝낸다.

2025.12.7 Update

Added code and an explanation for BigInteger in the 4-8 DP section - thanks to xuv2‑nim

2025.12.13 Update

5-4 Input/output case correction - thanks to June‑nim

2025.12.24 Update

3-5 Input/output case fix - thanks to giving0414.

2026.02.05 Update

3-5 ➕ Isn’t there a way to improve it further? Input/output case revision - thanks to junnkyuu.

2026.03.08 Update

5-9 Added an explanation and course material on how to handle failing Programmers test cases - thanks to giving0414.

2026.03.11 Update

1-10 Description revised - thanks to Kim Ji-hyeop.

2026.04.25 Update

Added Q&A about two-pointer techniques in 2-10 - thanks to Myeongseok.

The person who created this course

• 2021 ~ 2022: S Coding Club Algorithm (data-structure) Tutor

• 2022 ~ : Runs the coding YouTube channel DingCodingCo (featuring a variety of content related to developer employment)

• 2022 ~ 2023: Server Developer at Viva Republica

• Never give up on a student 🦈

• Operates a developer job-hunting community

  
  

  • ✅ Join the KakaoTalk chat: https://open.kakao.com/o/gPI6kTUg

    
    

  • ✅ Join Discord: https://discord.gg/X74q5Yw3Sv

    
    

Notes Before Enrolling

If you have any doubts!! before enrolling.

Should I be taking this course right now?? If you’re wondering, please feel free to contact us anytime via the KakaoTalk channel!!

😍 I’ll do my best to answer your questions 😍