It is not only Hao Yun's parents who are watching the CCTV interview, but also Hao Yun's three sons in the 401 dormitory, plus a little fat man Zhou Xuan who always comes to 401 to sleep.

"Brother Yun's cow pie! This has to break the Guinness World Record for the fastest delivery time in the Hope Cup, right? Looking at Hao Yun who came out of the gymnasium, Zhou Xuan couldn't help but shout.

"And this record?" Liang Ziyuan asked.

"Hehe, we can apply for him." Zhou Xuan smiled embarrassedly and said.

"But what the host said...... The main examination committee is in session, what are you going to discuss? Zheng Xueqian touched his chin and frowned in thought.

"Hell knows, maybe some terrible answer was written." Zhou Xuan shrugged his shoulders and said helplessly.

The answer?

What could be the answer?

Including Zhou Xuan himself, who threw out this sentence, all the people gathered in front of the computer had curious expressions.

At the same time, in the office of the School of Mathematics of Jiangcheng University, Professor Li Xuesong, who was flipping through his papers, suddenly received a call from the Xia National Institute of Mathematics.

The caller is Professor Liu Shoufeng, a big star in the field of number theory in China, and also the author of the last big question in the previous college student mathematics competition.

On the caller ID on the mobile phone, Professor Li Xuesong was too lazy to answer, but thinking that this old man was not an ordinary cautious eye, he still patiently pressed the button to connect.

"Hello? What's the matter, Lao Liu? ”

"Did you read the email I sent you?"

"Mail?"

"I just sent it to you!"

I don't know what medicine this old guy has buried in his stomach, Professor Li Xuesong opened the mailbox with a stomach full of questions, and sure enough, he saw an unread email.

Good guys, 1 minute before the shipping time?

It's not that there is a message reminder on WeChat, how can the ghost see your email!

He rolled his eyes and opened the email, but Professor Li Xuesong, who saw the contents inside, was stunned.

The text has only one string of characters of unknown meaning - 0x5f375a86

"Is this a hexadecimal number?" Touching his chin, Professor Li Xuesong's face was full of interested expressions, "Is there any mystery in this number?" ”

Every time Liu Shoufeng, the old thing, calls him, it is nothing more than two things, either to show off, or to share the latest discoveries. In the past, he could see some clues, but he looked at this number for a long time, and even silently made decimal and binary changes in his heart, and he didn't feel anything different.

Professor Liu Shoufeng on the other end of the phone smiled: "Sure enough, even you can't see what's special about this number!" ”

"You old thing doesn't sell much, if you have a fart, hurry up and finish it once, and I'll hang up if it's okay!" Professor Li Xuesong said with a smile.

"Hang? Then you will definitely regret it! Don't talk nonsense with you, do you remember the Newton-Laphsson method? ”

"Nonsense, who doesn't remember this!"

The Newton-Laphsson method, a method proposed by Newton in the 17th century to approximate the solution of equations in the field of real and complex numbers, is rarely used by those who study pure mathematics, but it is widely used in the field of computers.

For example, if you want to calculate the value of √2, first guess a random number such as 4, there is no doubt √that 2 cannot be equal to 4, but as long as you use the Newton iterative method to iterate all the time, after n steps of iterative operation, you can always calculate 1.414 ....... And if you use 2 as a guess, because 2 and 1.414 are close enough, it only takes two iterations to figure it out.

Li Xuesong remembered that he seemed to have talked about this knowledge point more than once when he was in class with computer science students, but he really didn't know what to dig into this thing.

Professor Liu Shoufeng: "I just sent you another email, which contains a piece of algorithm that has been translated into mathematical language, and you will know why I am so surprised by this number after reading it." ”

Hearing this, Professor Li Xuesong couldn't help but roll his eyes, but he couldn't hold back the curiosity in his heart, so he clicked on the next email as he said.

The whole algorithm itself is not difficult, but it is just to find the reciprocal of the square root. Professor Li Xuesong even felt that even if he did not translate into the language of mathematics, he could understand it completely.

To put it simply, that 0x5f375a86 is a constant used to calculate the guessed value.

Because using Newton's iterative algorithm to find the square root reciprocal first requires a guess value, which is usually determined by a series of calculations based on the value entered by the user.

Professor Li Xuesong made up a random number and tried to use the algorithm to find the reciprocal square root.

But that's when something magical happened!

He found that no matter what value he entered, the guess value was so close to the end result that the entire algorithm only needed to be executed twice at most to end the loop.

And the reason for all this is because of that 0x5f375a86!

"Incredible...... "Incredible" gradually discovered the mystery, and Professor Li Xuesong muttered to himself, "How did this number be discovered?" ”

His mind was full of one question right now.

Why 0x5f375a86?

Professor Liu Shoufeng said in a joking tone: "I have to ask you, after all, it is your students who make the 'trouble'." ”

Hearing this, Professor Li Xuesong was shocked.

"My students? Are you sure? ”

What the hell?!

Why didn't I know I had such awesome students?

"That contestant named Hao Yun is not your student?" Suddenly, as if remembering something, Professor Liu Shoufeng patted his head, "Oh, I almost forgot, the one you named is the main examination committee of the mathematics competition...... Hope Cup is engaged in programming, and it seems that it really has nothing to do with you. ”

"Wait, you said Hao Yun? Hope Cup? What does that mean exactly? Professor Li Xuesong asked confusedly.

Professor Liu Shoufeng patiently explained: "In short, there is a question in the Hope Cup competition, which requires improving the operation efficiency of a software. So far, your student has made it, and the solution has surprised everyone. Usually the idea of a coder should be to start with code, right? As a result, he went directly to modify the code of the underlying function, so that the function that originally required a few more steps to calculate was now completed in two steps. ”

Professor Li Xuesong was stunned, and it took a long time to hold back a sentence.

“…… Is it so awesome? ”

"Yes, it's not just, none of the old guys in the main examination committee figured out what this number was, and then sent an email to our Xia National Institute of Mathematics, but I didn't see anything famous after reading it for a long time."

As he spoke, Professor Liu Shoufeng sighed and continued.

"It reminds me of the famous Basel problem, that damn infinite series ∑ 1/n². No one knows why the first person to find it converging to π²/6 would be bored enough to memorize the value of π²/6. You know, that's an irrational number, who doesn't have anything to remember that? But the annoying thing is that he just knows! And it turned out to be true! ”

"We have to admit that some people in this world are indeed sensitive to numbers, even beyond the understanding of ordinary people, to the level of intuition...... At least, that's all I can explain until I talk to that student of yours in person! ”

Meanwhile.

Thousands of miles away in Shanghai.

The young lady who was squatting outside the lounge of the gymnasium finally waited for the opportunity to open the door.

Without hesitation, she immediately caught a man in a plaid shirt who was coming out of the background.

Judging by his orientation and dress, he should be a software engineer.

In this way, I wonder if I will know some inside information!

"Hello sir, I am a reporter from CCTV's education column, may I interview you, what kind of answer did that contestant submit, so that the main examination committee needs to meet to discuss...... Is there any news you can reveal? The reporter's young lady asked curiously.

The man didn't want to be interviewed, but after seeing the logo on the microphone, he showed a hesitant expression on his face and finally spoke.

"The competition is still going on, and I can't give too many details on my side, as for the contestant you mentioned...... What is surprising about him is that his answer can be said to have changed by only one number. ”

"One, a number?!" The reporter was shocked.

Even the photographer behind her had a surprised expression on his face.

"Yes...... I was surprised, and I could even say, that it was completely unexpected. It will not only affect glacier engines, but also products in other fields. ”

When he said this, the face of the man, who was presumably a software engineer, was half solemn and half helpless.

"Anyway, it's beyond my own knowledge. After a while, the professors of the mathematics department of Xia Dong Normal University will come over, and they seem to have set up a temporary expert group on their side. You might as well ask their opinions, and maybe you can give you a reasonable answer? ”