(2026 Latest!) Pass the Information Processing Engineer Practical Exam in One Week

Hello, this is Weekend Coding.

As the exam approaches, many questions are being posted on the bulletin board.

I am also doing my best to provide answers, and I plan to respond almost in real-time right before the exam.

Having taught more than 5,000 students online,

As someone who has produced successful candidates for the Information Processing Engineer practical exam through offline tutoring as well,

I would like to talk about two different learning methods.

1. Use external materials and code for reference only.

Among the Information Processing Engineer practical exam questions found online, there are many cases where the code does not even run.

In particular, some sites operated in a question bank format may have incorrect code uploaded,

In some cases, even the preprocessor notation is incorrect.

I explain all codes only after directly executing and verifying them myself.

(However, it may differ slightly from the actual exam questions. This is because I also rely on questions reconstructed by students.)

This is because I reconstruct the problems based on those restored by students, while making estimations for any parts that were incorrectly restored.

What I can say for certain is,

It maintains a much higher quality than the irresponsibly posted code found elsewhere,

The point is that there is a guarantee that at least the output values are accurate.

2. Do not trust LLMs like ChatGPT.

For a long time, there have been people pointing out that the answers or explanation methods of ChatGPT or Claude are incorrect.

I am also human, so there may be some typos in the questions.

However, you should never absolutely trust the LLM regarding output values.

The image above shows one of the past exam questions from 2025.

These are the results of entering the input into an online compiler and GPT-5.4 Thinking, respectively.

While the online compiler outputs 3 and 2,

ChatGPT outputs 2 and 3.

LLMs do not execute code directly.

Unless you explicitly request it to "run the code directly to verify," it will not execute the tool.

I have witnessed several instances where LLMs produce incorrect answers for complex recursive functions or unusual data structures.

In the process of creating lectures or answering questions, I have also experienced far too many situations where the LLM provides incorrect answers.

I am an instructor for the Information Processing Engineer practical exam, but I am also someone who develops personally.

In my daily life, I engage in agentic coding, consuming hundreds of millions of tokens using models like Claude Sonnet, Codex, and GLM-5.

Nevertheless, I do not have blind faith in LLMs.

This is because it makes mistakes far too often.

If I am wrong, I would appreciate it if you could verify it yourself and then post your question.

And there is one thing I would like to ask of you.

Never use LLM output as your primary basis for learning.

If you do that, you will get it wrong on the exam.

The Human Resources Development Service of Korea does not use ChatGPT for grading.

Additionally, if the code output varies depending on the compiler version, everyone will be marked as correct.

So don't worry, and you can write your answers with confidence at the testing center.

Surprisingly, there were many cases where everyone was marked as having the correct answer.

I hope you have a happy day today, and I am rooting for everyone to pass!

If you have the time, I would really appreciate it if you could leave a positive course review..^^