"Tsk, I only heard Mr. Cai say that he was self-taught, but I didn't expect him to be so self-taught. Pen @ fun @ pavilion wWw. ｂｉｑUｇE。 ｉｎｆｏ”

"was abducted and trafficked abroad as a black household, not only did he not degenerate and wander around, but he learned a skill and returned to China, which is too awesome!"

"It turned out that I taught myself in RB, no wonder I was stronger than us, RB conditions are so good, I may be better than him when I go. ”

"You smuggle it and try it, even if you don't starve to death for a week, you're amazing!"

Chen Zhiyang held the microphone with his left hand and raised his right hand flat, made an inviting gesture to Du Qiu, and at the same time said a few finishing touches: "Tianxingjian, a gentleman is constantly striving for self-improvement, Du Qiu's character of self-reliance and self-improvement, self-esteem and self-love is very worthy of your learning! ”

When Du Qiu joined the work after graduating from the bachelor's degree, the company's R&D department had to give an internal technical speech every week, so that employees took turns to give lectures, and they spoke no less than 10 times in two years.

He wore a long-sleeved shirt with blue stripes, covered with an iron-gray vest woven by Du Chunhua, with a long figure, a calm bearing, like pine and bamboo, proudly straight, as soon as he appeared on the stage, it immediately caused a round of applause, which was also mixed with the cheers of some male students, as for the female classmates, there were too few, there were only more than twenty in total, and they were weak, even if someone applauded, they couldn't hear it.

Zhang Dongliang, who was standing in the last row of the hall to help maintain order, applauded and said to Xiao Jialin: "It's really like a star." ”

"What? ”

"In the morning, you said that Du Qiu is very attractive, like a movie star, it really looks like!"

Chen Zhiyang did not rush down, but stood side by side with Du Qiu very closely, enjoying the enthusiastic applause of the students, and after the applause stopped, he picked up the microphone and continued to break the news: "In addition to self-reliance and self-improvement, I also hope that you can learn from his humble and sincere character, you may not believe it, the ticket for this speech, that is, the notebook cover you held, every word on it is handwritten by Du Qiu one by one......"

"Wow! He wrote such beautiful words himself?"

"I can only use the lines in "The Story of Deer and Ding" to describe my current mood: my admiration for this person is like a surging river, endless, as if the Yellow River is overflowing, and it is out of control!"

"This young man is really not simple, not only taught himself programming, but even wrote calligraphy so well, and I don't know where Lao Chen found it. ”

"Teacher Hou, how do you read this writing?"

"I don't know calligraphy, but it's rare for a young man in his twenties to be able to write such characters. ”

Chen Zhiyang felt that the scene was almost warmed up, so he handed the microphone to Du Qiu, patted his back lightly in the posture of an elder promoting a junior, and advised: "Speak well, relax and don't be nervous." ”

"I will. ”

Du Qiu walked to the center of the podium, stood in front of the multimedia table with a laptop, ready to give a technical speech, before opening the PPT file, he cleared up: "Principal Chen has a good reputation, I don't have any good qualities worth learning, it's just that after eating enough and dressing warmly, I did something that I was interested in, which is essentially no different from those who walk birds and fight dogs, so don't fantasize about other people's hardships and hardships to move yourself, it's meaningless." ”

In 2016, the chicken soup was flooded, so there were many people who were disgusted, but 1995 was the era when "Chicken Soup for the Soul" had just begun to become popular, so these words were not only out of place, but also a little deviant, which suddenly dispelled the warm atmosphere that Chen Zhiyang had just set up, and there was a buzzing discussion in the hall.

Du Qiu turned a blind eye and continued: "Before I speak, I want to state three things. First, applause and loud noises are allowed, but you can communicate in a low voice without disturbing others; second, if you have a question, you should raise your hand first, and I will ask a question after I agree; third, if you have something or don't want to listen, you can leave through the front or back door, and do not disturb others when leaving. ”

He looked around the hall, paused for a few seconds, and after the sound of the conversation had subsided, he nodded to himself and said, "Since everyone is not against it, then I will start." ”

"Open source software is a concept that I proposed, and I am honored and grateful to President Chen for inviting me to explain some relevant knowledge to you...... If you are interested, you can go to Mr. Cai to get a printed brochure after the lecture, and take it back to read it yourself, so I won't go into details. ”

"All of you here are either students or teachers, so I'm going to talk to you today about the benefits of open source software in teaching. ”

Du Qiu clicked on the first PPT, projected the code on the promotional poster on the screen behind him, and said: "This code is the standard answer in many C language textbooks in China, but it has the problem of time complexity, and it is absolutely impossible to use it in actual software development......

There was a soft laugh in the hall, but Du Qiu ignored it and continued: "But when you were studying, how many questions did you consider the complexity of time?"

The chuckle suddenly stopped.

"This code has been posted on campus for 3 days, and many students have given optimized answers, and some have adopted the method of dynamic programming, saving the intermediate items that have been calculated before, and looking them directly in the next calculation to avoid double counting......"

Zhang Dongliang looked at the code on the screen, touched Xiao Jialin lightly, and said in a small but somewhat proud voice: "It's the same as the code we optimized." ”

He said that most people do this, and there should be other ways to optimize it. ”

Du Qiu clicked on the screen again, switched to another optimization method, and then introduced: "There are also some simpler ways, from the top to the bottom, using loops to achieve recursive ......"

Xiao Jialin smashed his left hand with a fist with his right hand, and said with some annoyance: "This method is indeed simpler." ”

His frustration was not over, and immediately turned into surprise, because Du Qiu showed another optimization scheme, which was very long in code, but greatly reduced the time complexity from o(n) to o(logn).

"Damn, I don't understand how this is optimized. ”

"I don't understand it either. ”

Du Qiu picked up the thermos cup that Du Chunhua arranged for him to bring over to advertise in advance, took a sip of water, and let the audience in the lecture hall have time to read the code, and then explained: "This is a special optimization scheme designed by me, which requires a certain mathematical foundation......

He first introduced a matrix formula, and then explained the code, which was very concise, Zhang Dongliang was not very good at mathematics, he didn't understand, and he was a little puzzled: "It's just a Fibonacci sequence, is it necessary to make it so complicated?"

Xiao Jialin understood, and felt that Du Qiu must have another deep meaning, so he was silent and did not answer.

Sure enough, after Du Qiu finished explaining, he said: "You may think that this optimization method is a big fuss, and you are full of food, but in fact, this optimization method can touch the class and play a role in other places, such as calculating the integer power of the value, I will give you 10 minutes for this topic, you think about how to program." ”

Zhang Dongliang looked up, and saw a problem on the curtain, which was a bit similar to the one on the bookmark, all of which were designed to implement the function of a certain library function in the C language, which also belonged to a very simple problem at first glance, but very complicated when thinking about it, he took out a pencil, leaned against the cool wall, and scribbled on the notepad for several minutes, but felt that his brain was a mess and could not be solved at all.

Du Qiu did not stand stupidly on the podium, and stepped off the podium, and under Chen Zhiyang's introduction, he met the teachers and professors sitting in the front row one by one.

Although he only spoke for less than ten minutes, he showed good strength, because the third optimization method is very cold and complex, using the knowledge of advanced mathematics, not only the students did not expect it, but the teachers and professors did not expect it, there is naturally no one who slacks off, all of them are very enthusiastic, some encouragement, some appreciation, only Academician Hou is not satisfied, and said: "Xiao Du, you abducted Dayou to the United States to work, so that I have one less good student, should I show something?"

"What do you want?"

"I like to play chess, but there are no suitable chess friends in the institute, Dayou said before to help me write a program that can play chess with the computer, and I haven't written it well for half a year, so it's better for you to write one for me, if it is written well, our grievances will be written off. ”

"Okay, that's a deal. ”

"I have to explain in advance that if the program you wrote is a stinky chess basket, I don't recognize it. ”

"Guaranteed, not. ”

Du Qiu chatted for a while, and after Jiang Danfeng made a hint that the time had come, he walked up to the podium again, knocked on the microphone, and asked, "Has anyone written it?"

After two rounds of screening, the students who can come in to listen to the speech are relatively capable, so many people raised their hands, Du Qiu randomly selected a few students, and asked them to hand in the answers, but did not announce whether it was right or wrong, but switched to the PPT document, and explained the two pieces of code they wrote, the first paragraph uses the traditional method to solve the problem, the code has dozens of lines, cumbersome and inefficient, and the second paragraph uses the mathematical formula just now to solve the problem, the code is only a few lines, concise and efficient.

After the explanation, Du Qiu called up the original code on the promotional poster and concluded: "I used this code as a poster to let everyone know the three benefits of open source software. ”

"First, the knowledge in textbooks and the needs in production are two different things, the computer is a productivity tool, not a toy on paper, only understand the theory and do not understand the practice is not good, but with the current environment in China, it is difficult for students in school to have the opportunity to actually develop a mature software, if you don't want to be a nerd, the only way is to read excellent open source software code, understand what real software development looks like. ”

"Second, computer software is a very innovative industry, and if you want to innovate, you must first have accumulation, writers can read the works of Cao Xueqin or Tolstoy, mathematicians can read the works of Gauss or Euler, physicists can read the works of Newton or Einstein, and what do programmers rely on to accumulate? Only by looking at the code of open source software, such as this formula, which I found from the recursive function of some open source software. ”

"Third, writing open source software will make you progress faster. Du Qiu picked up the answers handed over by the students just now, raised them in the air, and said: "If you knew that I would post these answers on the wall for everyone to see, would you think more rigorously? Write more carefully? If many people point out the mistakes in the public, will you seriously reflect on them? Don't make the same mistakes again?"

These three benefits are very simple, even if you don't say that the students here all understand, but after the personal experience of the past few days, everyone has a deeper understanding and understanding, the lecture hall is silent, and many people have thoughtful expressions on their faces.

Next, Du Qiu switched the ppt to the topic on the bookmark and explained it, Xiao Jialin only listened to two sentences, and sighed: "No wonder Mr. Du said that I am barely a qualified code farmer, we did not take into account the judgment and overflow of the maximum positive integer and the minimum negative integer." ”

Zhang Dongliang nodded silently.

"Now the software is becoming more and more complex, dozens or even hundreds of employees working together has become the norm, software companies need to have teamwork talents, not a lone hero, if there is no good programming habits, consider the problem full of loopholes, a patch here, a bug there, not only the boss will beat you, colleagues will also use the keyboard to smash you. ”

"This title on the bookmark is to tell you another benefit of open source software, that is, to increase your horizons, distinguish between good and bad, and distinguish between good and bad programming habits, because there are many open source software projects that strangers work together, and if the programming habits are not good, it is difficult to cooperate with others. ”

Speaking of this, Du Qiu picked up a C language textbook from the podium and said: "I don't know the author of this book, so I don't make an evaluation, but I can tell you responsibly that when you finish reading one or several excellent open source software codes, if you can't find more than 200 errors, omissions and fallacies from this book, you are not a qualified computer student, because the programming thinking, programming style and programming habits shown in this book are extremely bad!"

As soon as the words fell, only to hear a buzz, the entire lecture hall was boiling, because the textbook is very famous, the circulation is huge, almost all universities and ordinary programming enthusiasts in the country take it as an introductory textbook, and there are many provincial and ministerial level senior officials and academician-level celebrities for its inscription, can be described as the most authoritative C language textbook in China, but it was so disdained by Du Qiu, naturally caused great controversy.