Scholar’s Starry Sea

"So you want us to help you improve the plagiarism detection tool?"

"Well, it's a big deal to get it done, I promise you will study it ……Well, you are not short of scholarships. I will invite you to dinner when I return to Shanghai. How about Jin Mao’s top floor?"

"Wow, is it such a luxury."

"Yes, this is a big project, how about it, please do me a favor?"

"Okay, I will try it, but let me talk about it first, the programming language is not what you imagined It’s so powerful."

"You are better than you think." Li Yan shook his head. Although Wu Bin didn’t help him solve any practical coding problems, Li Yan’s academic ability I'm so relieved, but everything that this big guy has studied hard can reach realm that ordinary people can't understand.

Both of them belong to swift and decisive characters, so after eating, Wu Bin and Lin Ziqi directly followed Li Yan to the student union office.

【Should shoulder the mission of the times, gather the power of youth! 】

As soon as you enter the door, you are full of various party newspapers and propaganda posts, which can be said to be quite popular, and it makes people feel full of mission at a glance.

Under the leadership of Li Yan, Wu Bin met Tang Chengwen, the vice chairman of the Discipline Inspection Department.

When learning that Wu Bin was here to help solve the problem, Tang Chengwen immediately expressed a warm welcome.

Last semester, Wu Bin learned from Li Yan that the Student Union of University of Science and Technology does not have the legendary "bureaucracy". Everyone regards the Student Union as a place to exercise their abilities. , So the atmosphere is very good.

Although Wu Bin has also heard that some students will become official after joining the student union, and even do some party and private affairs after they are in power, but it is really hard for him to imagine what it will be like. scene.

After a few words of kindness to each other, Tang Chengwen explained to Wu Bin the phenomenon and scope of cheating.

Wu Bin listened completely nodded.

In short, he does not need to study how plagiarism occurs, he only needs to develop a better automatic program to effectively find out the copied code from a bunch of submitted jobs.

'Interesting'

This reminds Wu Bin of a small game he encountered on the forum. The content is to give you two copies of C code, and you give the difference between them. A score for similarity is an effective training for language understanding.

"Let me try."

The expert Wu Bin in the code world has seen a lot in major forums, but he is now at the University of Science and Technology, and will I really don’t know what kind of cultivation the old monster of Montenegro has encountered.

"It's so smart..."

After brushing a few sets of codes, Wu Bin's mouth is cocked. The code writer obviously knows that someone will check the similarity of the code, so Deliberately changing the code is complicated. If you want to manually one after another to identify it, it is really time-consuming and laborious.

In addition, there are many students who directly copied the code. It is estimated that they are all holding thighs. It can be said that it is completely reap without sowing. Although this is human nature, it is definitely not a good behavior. .

'However, the design of this experiment is indeed a bit boring, and it is estimated that most students are not interested in doing it seriously. '

But what is wrong is wrong, and it is certainly not good for school to develop this habit.

"How is it, is it difficult?" Tang Chengwen asked, standing behind him.

"It's okay, just give me some time."

"Then it's very good." After Tang Chengwen finished speaking, he asked Li Yan in a low voice: "You still know friends from Xinyuan ?"

"Oh no, he is my classmate, Wuyuan."

"Wuyuan is so versatile now!?" Tang Chengwen surprised.

"No, he is the only one. He has a wide range of hobby interests."

"Excellent..."

Wu Bin is doing questions in the chat room between the two Analysis, in essence, the problem of checking and copying codes is actually given two codes P1 and P2.

Require d(P1, P2) the "distance" between them. The smaller the distance, the greater the suspected plagiarism.

The premise of solving the problem is naturally to find the problem. Looking at so many codes at present, Wu Bin almost made a summary in his heart.

The most used method is to modify irrelevant information such as comments, variable names, and capitalization. Then there are code rearrangement, style modification, etc., for example, use the indent tool to filter the code. You must know that everyone has their own programming style. With this change, naked eye looks very different.

The other two are more technical. One is to add or delete redundant elements in the code, such as adding some useless code, or deleting some printed debugging information.

The second is to do equivalent rewriting, splitting, and merging functions for data structures, loops, and local codes.

To find out the problem, the first thing Wu Bin needs to do is to optimize the compiler to compile the code. This is very important. Many equivalent codes that have been manually modified can be optimized into the same binary code, and then Get the command sequence of the function.

In this way, apart from the most technical method of rewriting data structures, loops, and partial codes, the other three cheating methods are useless.

Because in the eyes of the compiler, regardless of how you indent or adjust, the compiled function looks the same.

Looking at Wu Bin crackling code on the computer, Tang Chengwen and Lin Ziqi both opened their mouths behind.

Lin Ziqi knew that Wu Bin had a good design procedure when he was in the laboratory, but now he sees it with his own eyes and still feels shocked.

'This proficiency is too high...'

After modeling the similarity of the program to the maximum weight matching problem of a bipartite graph, Wu Bin turned to Tang The written text said: "I want to copy the rest back to the dormitory. I guess it will take a lot of time, okay?"

"Of course there is no problem." Tang Chengwen repeatedly nodded, "Then I will thank you first. Help us solve such a big problem."

Although Tang Chengwen could not understand what Wu Bin did, his calm and composed appearance made him think that someone who had no abilities really pretended not. come out.

"You are welcome."

In the past week, Wu Bin has been reading Physics papers frantically. Now that he stops to do something else, it makes him feel good and even feel some new inspiration. It's already in gestation, and if you work harder, you can come up with it.

Leaving the student union, Lin Ziqi left the team and went to the laboratory, while Wu Bin and Li Yan returned to the dormitory.

Turn on the computer, Li Yan turned around and said to Wu Bin: “I finally know why so many people like to use it. B."

Before Wu Bin could speak, Chen Anzhi on the side interrupted and said: "Why, God Wu took you to pretend to be B and fly you?"

"Yes Yes, it may not be long before the student union will circulate the legend that I have an amazing roommate."

"What kind of B? Let's listen." Chen Anzhi looked curious.

"It hasn't been solved yet, don't listen to him." Wu Bin said as he walked to Chen Zhian's desk and glanced at the electromagnetic problem he was doing.

"Big guy...Don't look at me like this, I'm so stressed." Chen Zhian said pitifully.