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) 401 reviews

2,572 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 following companies.


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

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


Are you wondering if this is an old story? I changed jobs by taking coding tests through 2024. As of now, I have experienced the coding tests currently being administered by companies. That is why I know what and how much you need to prepare.

Meaningless coding test preparation? You don't need it anymore. I will teach you exactly what you need to know to get hired. Learn compactly and pass all your coding tests.

A collection of real reviews from students who passed after taking the course

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

2025/07/31 Final acceptance at 3 companies, Ohxx-nim

✅ Here is what you will learn.

Algorithms Made Easy with Real-Life Examples

  • Capsule hotels and cargo holds

  • Laundry baskets and amusement parks

  • The emergency room and the shortest path to work

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

Algorithms Made Clear Through Visualization

  • Sorting processes viewed through animation

  • Understanding tree structures through diagrams

  • The operational principles of stacks/queues changing step-by-step

  • Understanding DFS/BFS search processes through illustrations

Preparing for Real-world Coding Tests

  • Solving actual past exam questions from Kakao, LINE, and Samsung

  • Analysis of the latest exam trends by company

  • How to find hints within a problem

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

Continuous Growth Support

  • Providing an active online community

  • Real-time Q&A and feedback

  • Sharing and discussing various solutions

  • Vivid reviews from successful candidates by company

Features of this course

📌For Beginners (No Base)

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

  • We explain 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 video of the algorithm's solution at the end of the video.

📌Just jumping straight into solving problems? Absolutely not.

  • Rather than simply solving the problem, I will guide you step-by-step through the mindset of how to approach and resolve the problem once you see it.

  • Algorithm problems are not designed for math geniuses to solve. Brilliant ideas? A "Eureka" moment? Absolutely not.

  • Each element that makes up a problem contains hints on what process to follow to solve it. I will show you how to pick up those hints.

📌 Community Management

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

  • This can naturally happen 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.

📌 60% Theory, 40% Practice

  • This curriculum starts with detailed theoretical explanations and ultimately progresses to solving actual exam questions from companies.

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.
✔ For those who want to properly understand the process and principles of problem-solving

Studying alone is too difficult
✔ 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 43M KRW)

Actual successful student Oxx (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.

Out of the 38 coding tests I've taken, I've only encountered that in 2 places.

Almost all of the places 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're worried because it's not a language you've already learned.

However, I believe it is necessary to understand it in the easiest way possible using Python.

Algorithms are already difficult enough, and if complex syntax is mixed with difficult logic, it becomes much harder to read the code.

When you first start studying, it is best to understand things as easily 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, and understanding the problem is what matters most.

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


[Updated July 20, 2025]

We have added additional code so that you can solve problems using Java and JavaScript, as many students have requested!
Please note that we haven't added explanations for these specific languages; instead, it would be great to use them as a way to review by comparing them with the same logic in other languages!

🎁 EVENT 🎁


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

There are carefully selected special algorithm problems based on actual questions received while reviewing 38 real-world coding tests.


Please think of it as a spe-cial problem set created for those who want to practice additional problems beyond theoretical learning.
This problem set will be continuously updated, so you will be able to prepare for algorithms in line with the latest trends!!

(This workbook will be provided as a Notion link!)


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

Thank you.

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

(I have included the instructions on how to verify in the very last lecture __)


That's not all.

We will even provide a developer job preparation guide (resume, portfolio, etc.)!


🎁 EVENT 2 🎁

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

In return, we are sending a coffee gifticon as a token of our gratitude.


🎁 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: 3-month free trial for a single JetBrains IDE (e.g., IntelliJ, PyCharm, WebStorm, etc.)
Expiration Date: ~ Until May 13, 2026
How to Use😀

1. Access the official JetBrains coupon registration page

2. Enter the code and select the desired IDE

3. Check the license issued via email

Precautions:
This code is only available for new users who are using JetBrains for the first time.
(Only those who have 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 meticulous review, and all videos include subtitles.

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 high quality.


2. The textbook has a total of 393 pages.

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

2024.11.30 Update

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

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

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

2024.12.15 Update

Added textbook PDF download link

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 the 4-2 video - thanks to Aerong

2025.7.18 Update

Fixed error in selection sort output values 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 data structure libraries for practical use - thanks to 브루브루

2025.10.19 Update

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

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 ➕ Are there any ways to improve further? Input/output case correction - thanks to junnkyuu

2026.03.08 Update

5-9 Added textbook explanation on how to handle Programmers test case failures - thanks to giving0414

The person who created this course

Sharing the backstories of reaching the final interviews at Coupang and Yanolja - A 6th-year developer's story of applying to 24 companies [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 giving up on students 🦈

  • Operating a community for breaking into developer careers


Things to note before taking the course

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

Is this the right course for me to take right now? If you are having doubts, please feel free to contact us anytime through the Open Chat Room!

😍 I will do my best to provide you with answers 😍

Practice Environment

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

Learning Materials

  • Everything will be shared via Notion!

Prerequisites and Important Notes

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

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Learners

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Reviews

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Answers

4.9

Rating

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Courses

🚀 Ex-Toss, POSTECH graduate | Current Backend Developer (+8 years)
🎥 YouTuber with 20,000 subscribers | Development content creator
📚 Inflearn Instructor | Cumulative 15,000+ students
👥 Running a developer career community (8,000+ members)
🧩 Contributor to various open source projects (Gradle, Spring AI, etc.)
📝 Passed 38 resume screenings and conducted 100+ resume reviews on Kmong (5.0 rating)

I deliver vivid, real-world industry insights in an easy-to-understand and deductive manner.

Inflearn Interview Link!

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Curriculum

All

56 lectures ∙ (15hr 33min)

Published: 
Last updated: 

Reviews

All

401 reviews

5.0

401 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.

      • 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!

        • 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!!

        • 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

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