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The secret to passing 38 companies: Essential algorithms for the 2025 coding test

With step-by-step explanations that even beginners can easily understand, the once-vague coding tests will become clear. Learn only what you need and apply it to real-world practice right away!

(5.0) 398 reviews

2,547 learners

Level Basic

Course period Unlimited

Python
Python
Coding Test
Coding Test
Algorithm
Algorithm
data-structure
data-structure
Python
Python
Coding Test
Coding Test
Algorithm
Algorithm
data-structure
data-structure

Reviews from Early Learners

Reviews from Early Learners

5.0

5.0

이한희

73% enrolled

While I was busy with a project, I didn't have time to prepare for a coding test, so I was looking for a place to prepare quickly in a short period of time when I applied for a job, and I found out about DingCodingKo's lecture that I usually enjoy, and I purchased it and am taking the course. It is most important to do algorithms consistently, but I think it is a good lecture for those who need a systematic curriculum to study in a short period of time like me. The official curriculum period is a 5-week lecture, but the explanation is good, so you can quickly learn the theoretical content, and assuming you invest a little more time, I think it will be enough to study in 2 weeks if you have coded before. The theoretical study and simple practice are good, and it is also good to solve the problems that came out in the actual coding test in the last week's lecture. If I listen to all of this lecture and solve coding test problems on my own, I think my worries about coding tests in employment will be reduced!

5.0

자유곰

9% enrolled

Hello. I am a developer preparing for a job change. I have been learning algorithms from Baekjoon and Programmers for a long time, but I couldn't motivate myself to do it alone, so I looked for a lecture. Since I am currently using JAVA, I initially thought that Python was a language that I would learn later. However, after taking a sample lecture on other algorithms and being dissatisfied, I watched Dinkocodingko's sample lecture. The reason I decided to pay right away is that the tone of his voice suited me so well. I should say that it went straight into my ears? I was worried because I usually pay a lot of attention to the teacher's learning method, but it suited me so well! Since the tone of his voice is so good, I don't get sleepy, I can concentrate well, and it goes straight into my ears 😊😊 However, it's not just the tone of his voice that's good, but the way he teaches is not just about solving problems, but he really teaches about algorithms in detail, so I'm satisfied. I will definitely finish the course and try to change jobs 😊😊

5.0

가람

18% enrolled

It's been quite a while since I systematically studied algorithms. In practice, I often use libraries or frameworks, so I have fewer and fewer opportunities to directly contemplate and implement algorithms. This lecture allowed me to reorganize from the basics. In particular, I was impressed that it not only explained the concepts but also covered the way of thinking and approaches to solving problems in detail. Thanks to this, I was able to not only recall the concepts I had forgotten, but also regain the habit of thinking about how to write more efficient code. I think algorithms are not just for coding tests, but also greatly help to improve problem-solving skills. After building my basics through this lecture, I feel more confident in approaching new problems in the future. I highly recommend it to those who want to review from the basics!

What you will gain after the course

  • Algorithm

  • Coding Test

  • Coding test

🎯 Coding Test Master Class perfected through 38 actual passes

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


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

Kakao Mobility, NAVER Webtoon, Works Mobile, Banksalad, Bucketplace (Ohouse) ...


Do you think this is an old story? I changed jobs by taking coding tests until 2024. I have experienced the coding tests of companies currently hiring. Therefore, I know what to prepare and to what extent..

Meaningless coding test study? You don't need it anymore. I will teach you exactly up to the range required for employment. Learn compactly and pass all your coding tests.

A collection of real reviews from those who passed their exams after taking the course.

2025/02/16 Travel Wallet Accepted **Hyun-nim

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

✅ Here is what you will learn.

Learning algorithms easily through real-life examples

  • Capsule hotels and cargo holds

  • Laundry basket and amusement park

  • The emergency room and the shortest path to work

  • Analogies and explanations that are impossible to forget once you've heard them.

Algorithms made clear through visualization

  • Sorting process viewed through animation

  • Understanding tree structures through diagrams

  • The step-by-step operational principles of stacks and queues.

  • Visualizing DFS/BFS search processes through diagrams

Preparing for Real-world Coding Tests

  • Solving real-world past exam questions from Kakao, LINE, and Samsung

  • Analysis of the latest exam trends by company

  • How to find hints for a problem

  • How to determine the solution based on the range of input values.

Support for continuous growth

  • Providing an active online community

  • Real-time Q&A and feedback

  • Sharing and discussing various solutions

  • Vivid reviews from successful candidates at various companies

Features of this course

📌For beginners with no prior knowledge

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

  • It explains in detail, starting from why this code is used and how to come up with that idea, to how the values actually change when the code is executed.

  • Since you might still find it difficult to understand, I have even included a visualization of the algorithm's solution at the end of the video.

📌Just jumping straight into problem-solving?Absolutely not

  • Instead of just solving the problem, I will guide you step-by-step through the mindset of how to approach and tackle the problem from the moment you see it.

  • Algorithm problems are not designed to be solved only by math geniuses. A stroke of genius? A "Eureka" moment? Absolutely not.

  • There are hints within every single element that makes up a problem on how to solve it. I will show you how to pick up those hints.

📌 Community Management

  • Nevertheless, there may be things you don't understand or questions that arise.

  • This can naturally occur due to the nature of online lectures.

  • That's why I've created a community where you can ask and answer questions in real-time.

  • Please feel free to come in and ask anything. Also, I hope you share and solve algorithm problems with various developers.

📌 Theory 60%, Practice 40%

  • This curriculum starts with detailed theoretical explanations and ultimately progresses to solving actual problems from corporate coding tests.

Recommended for these people

I don't know where to start with algorithms.

✔ Those who are new to algorithms and want to learn systematically from the basics

I don't understand the problem-solving process.
✔ Those who want to properly understand the process and principles of problem-solving

It's too hard to study alone
✔ For those who want a learning environment where they can grow together rather than alone

🥳🥳🥳 Real Student Reviews 🥳🥳🥳

Actual successful student Seong xx (Startup starting salary 43 million KRW)

Actual successful student Lee XX (Mid-sized company starting salary 48 million KRW)

😨Worry Point 1😨.
I heard that coding test languages are fixed these days?

I've heard that the language for the coding test is fixed depending on the stack you're applying for—like JavaScript for Frontend and Java for Backend?

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

I have taken coding tests at 38 different places and only encountered that in two of them.

Almost every place you apply to will have little to no restrictions on the programming language you use.

No matter how you express it, interviewers also know that the critical thinking skills to solve the problem are what ultimately matter.


😨Worry Point 2😨.
It's not my main language?

You might say you are worried because it is not a language you have already learned.

However, I believe that understanding it in the easiest way possible using Python is necessary.

Algorithms are already difficult enough; if you mix in complex syntax with difficult logic, the code becomes much harder to read.

When you first start studying, it's best to understand things as simply as possible, and then try expressing them in more complex ways later on.

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

If you have understood the logic with Python, you can definitely express it in Java.

😨 Ultimately, language is just a means of expression; understanding the problem is what matters most.

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


[Updated July 20, 2025]

I have attached additional code so that you can solve the problems in Java and JavaScript, as many students have requested!
While I haven't added explanations specifically for those languages, it would be great if you could use them as a way to review while comparing the same logic across different languages!

🎁 EVENT 🎁


There is a special benefit provided only to those who take the course.

There are specially selected algorithm problems based on actual questions received from participating in 38 real-world coding tests.


You can think of this as a special workbook created for those who want to practice additional problems beyond theoretical learning.
This workbook will be continuously updated, so you will be able to prepare for algorithms in line with the latest trends!!

(This workbook is provided as a Notion link!)


I will provide the workbook to those who write a course review!

Thank you.

Get it after verifying your course review in the algorithm community!

(I have explained how to verify in the very last lecture __)


That's not all.

We even provide a developer job preparation guide (resumes, portfolios, etc.)!


🎁 EVENT 2 🎁

After completing the course, those who have passed, please share your course review and career transition success story in the Open Chat Room!

Then, as a token of our gratitude, we are sending you a coffee gift icon.


🎁 EVENT 3 🎁

If you submit the Google Form through this link,

🎟 We will send you a discount coupon 🎟


🎁 EVENT 4 🎁


Pycharm IDE 3-month free trial voucher provided!

To support your development studies, I have prepared special benefits through a collaboration with JetBrains.
You can use PyCharm for free for 3 months using the promotion code below!


Promotion Code: HYUNJOONPARKxJB
Benefit Details: JetBrains Single IDE (e.g., IntelliJ, PyCharm, WebStorm, etc.) 3-month free trial
Expiration Date: ~ Until May 13, 2026
How to Use😀😀

1. Access the official JetBrains coupon registration page

2. Enter the code and select your desired IDE

3. Check the license issued via email

Precautions:
This code is only available for new JetBrains users.
(Only those with no prior history of using a paid JetBrains license can register)
(You can do this indefinitely by creating a new Google email account)

😆 Lastly, I would like to emphasize just two things.

1. This course has undergone two rounds of thorough inspection, and subtitles are included in all videos.

You might think, "Why does that matter?" but many lectures are often uploaded as they are without any review.

This course has been refined through a two-step review process, carefully checking subtitles and context to ensure a high level of quality.


2. The textbook has a total of 393 pages.

It is designed so that the content can be fully understood with the textbook alone. We have made every effort to organize and deliver the material systematically to help you save time and learn as efficiently as possible.

2024.11.30 Update

Among the course feedback, there was a comment stating, "I wish there were more example problems."

Reflecting this, I have added bonus problems throughout the lecture materials.

Please consider the problems marked with the 🎆 icon as bonus problems that do not have separate explanation videos.

2024.12.15 Update

Added a download link for the textbook PDF

2025.1.13 Update

3-5. Added explanation on how to further improve the stack - thanks to zz gg

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

3-9. Added explanation for the condition that among songs with the same play count, the song with the lower unique ID is included first - thanks to sonjs7554

2025.5.18 Update

Fixed animation error in video 4-2 - thanks to Aerong

2025.7.18 Update

Fixed the selection sort output error in the 3-3 textbook - thanks to Yoo Gaebal

2025.7.20 Update

Added Java and JavaScript problem-solving code

2025.10.15 Update

Comparison Table of Practical Data Structure Libraries - thanks to BrewBrew

2025.10.19 Update

Modified boundary value logic and added boundary value tests for Week 4 Homework #1 - thanks to Finish within a month

2025.12.7 Update

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

2025.12.13 Update

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

2025.12.24 Update

3-5 Input/output case correction - thanks to giving0414

2026.02.05 Update

3-5 ➕ Is there any way to improve it further? Input/output case correction - thanks to junnkyuu

The person who created this course

Sharing the behind-the-scenes story of reaching the final interviews at Coupang and Yanolja - A 6th-year developer's 24-company career change story [ep 5]

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

  • 2022 ~ : Operating the coding YouTube channel Dingco Dingco (featuring various content related to developer employment)

  • 2022 ~ 2023 : Viva Republica Server Developer

  • Never give up on a student 🦈

  • Operating a community for smashing developer job applications


Things to note before taking the course

If!! you are having even the slightest hesitation before signing up for the course.

If you are wondering, "Is this the right course for me to take right now?" please feel free to reach out via the Open Chat Room at any time!!

😍 I will do my best to answer your questions 😍

Practice Environment

  • We use PyCharm in this course. The educational (free) version is perfectly fine!

Learning Materials

  • Everything will be shared via Notion!

Prerequisites and Precautions

  • Basic Python knowledge (If you haven't learned it yet, you can watch the free Python lecture I made!)


  • If you can understand the Python proficiency test video, you are more than capable of taking this course. thì bạn hoàn toàn có thể theo học được.


Recommended for
these people

Who is this course right for?

  • Those who are just starting to prepare for coding tests

  • Those who feel overwhelmed by the vast amount of algorithm study.

  • Those who need problem-solving techniques that can be applied immediately in practice.

  • Beginners who require understanding-oriented explanations and a step-by-step approach

  • Those who want to learn only the core algorithms that reflect the latest exam trends

Need to know before starting?

  • Python learned just a little bit

Hello
This is dingcodingco

14,848

Learners

1,547

Reviews

291

Answers

4.9

Rating

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Courses

🚀 Toss, POSTECH graduate | 8 years backend
🎥20K YouTuber | Creating dev content
📚 Inflearn instructor | 14,000+ cumulative students
👥 Running developer job community (8,000+)
🧩 Multiple open source contributor (Gradle, Spring AI, etc.)
📝38 document screening passes & 100+ resume reviews on Kmong (5.0 rating)

Flipping coding upside down, DingCodingCo. Delivering knowledge that's easy and deductively understandable.
Đảo ngược lập trình, Dingco Dingco. Truyền đạt kiến thức một cách dễ hiểu và có tính suy luận.

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Curriculum

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56 lectures ∙ (15hr 33min)

Published: 
Last updated: 

Reviews

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398 reviews

5.0

398 reviews

  • gisu11028193님의 프로필 이미지
    gisu11028193

    Reviews 1

    Average Rating 5.0

    Edited

    5

    45% enrolled

    I kept putting it off every day, but I've pulled myself together and started again. If you're encountering this for the first time, I think this will be the best course. When it comes to solidifying the basics, I doubt there's a better course at this price. What I hope for: It would be great if there were courses on more advanced algorithms after the basics.

    • yjym33님의 프로필 이미지
      yjym33

      Reviews 29

      Average Rating 4.7

      5

      13% enrolled

      The instructor explained everything in detail, making it easy to understand even for those who are new to the subject. The visual aids at the end were also easy to follow, so it was very helpful. - What I would like to see: It would be great if there were explanations and problem-solving for complex algorithms that might come up on the CoTe, such as the Bellman-Ford, BFS, and Floyd-Warshall algorithms.

      • bhn19979793님의 프로필 이미지
        bhn19979793

        Reviews 2

        Average Rating 5.0

        5

        14% enrolled

        I got a job without majoring in it, but I wasn't very prepared for algorithms, so I'm taking this course to supplement it. It's really easy to understand with the abundant materials and explanations~!! I was worried because I didn't use Python in my work, but fortunately, it's an easy-to-understand language ㅎㅎ

        • dingcodingco
          Instructor

          bhn1997, I'm so glad you understood it well!! You'll definitely feel the advantages of Python as you code!! I really hope you can break the code through this lecture ㅎㅎ

      • lux님의 프로필 이미지
        lux

        Reviews 24

        Average Rating 5.0

        5

        7% enrolled

        I bought this course because of the thumbnail, but the content was even better. I majored in it and have experience as a developer, but algorithm problems were always difficult. I am gradually gaining confidence while taking this course😊 I set a goal of completing the course in 5 weeks, so I hope I can finish it well!! - Structure: Each topic is well organized step by step, so it naturally connects from basic data structures to actual past exam questions. In particular, I liked the fact that various approaches were introduced in the process of solving each problem. - Teaching ability: The explanations of the Dingcoding instructor are amazing, so it is easy to understand even complex algorithms. Even using visualization data👍🏻👍🏻 - Practical application: It doesn't stop at simply explaining the theory, but also covers solving actual problems and analyzing efficiency, so I think it will be very helpful for actual coding tests! Recommended for: I highly recommend this course to those who are preparing for coding tests or want to systematically build up their algorithm skills. If you have some understanding of Python grammar, I think you will gain a lot from this course. Rating: ⭐⭐⭐⭐⭐ (5/5)

        • dingcodingco
          Instructor

          ㅋㅋnim!! Thank you so much for the detailed course review!! 😭😭😭😭 I really hope it was helpful!! Keep up the good work!!

      • sethgots7214님의 프로필 이미지
        sethgots7214

        Reviews 1

        Average Rating 5.0

        5

        18% enrolled

        It's been quite a while since I systematically studied algorithms. In practice, I often use libraries or frameworks, so I have fewer and fewer opportunities to directly contemplate and implement algorithms. This lecture allowed me to reorganize from the basics. In particular, I was impressed that it not only explained the concepts but also covered the way of thinking and approaches to solving problems in detail. Thanks to this, I was able to not only recall the concepts I had forgotten, but also regain the habit of thinking about how to write more efficient code. I think algorithms are not just for coding tests, but also greatly help to improve problem-solving skills. After building my basics through this lecture, I feel more confident in approaching new problems in the future. I highly recommend it to those who want to review from the basics!

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