"Tsk tsk, I heard Teacher Cai say that he was self-taught, but I didn't expect that he was self-taught."

"Being abducted and trafficked abroad as an illegal householder, not only did he not want to fall into depravity and wandered around, but instead learned a lot of skills and returned to China. It's so awesome!"

"It turns out that I was taught by myself in RB. No wonder I am so awesome. The conditions for RB are so good. Maybe I'm better than him when I go."

"You smuggle over here and try it. If you don't starve to death for a week, you're awesome!"

Chen Zhiyang held the microphone with his left hand and raised his right hand flat, making an invitation gesture to Du Qiu, and at the same time said a few finishing touches: "Heaven moves forward, a gentleman strives for self-improvement, Du Qiu's character of self-reliance and self-respect and self-love is very worthy of your learning! Please come and ask him to give a speech to everyone, applaud and welcome."

When Du Qiu started working after graduating from undergraduate studies, the company's R&D department had to give internal technical speeches once a week, allowing employees to take turns to give lectures. After giving lectures no less than 10 times in two years, he had already experienced it. In addition, with the halo of confidence that travels through the party, he was not nervous at all. After teasing Jiang Danfeng leisurely, he stood up and walked onto the podium.

He wore a long-sleeved blue pinstripe shirt with an iron-gray vest woven by Du Chunhua. He was tall and calm, as if he was like a pine and bamboo, and he stood up proudly. As soon as he appeared on stage, he immediately caused another round of applause, mixed with some cheers from male students. As for female classmates, there were too few, only a dozen, totally, with weak power and slight words, and even if he cheered, he 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 really looks like a star."

"What? Speak louder."

"You said in the morning that Du Qiu is very charming, like a movie star, and it really looks like!"

Chen Zhiyang did not rush down, but stood shoulder to shoulder with Du Qiu very close, enjoying the warm applause of the students. After the applause stopped, he picked up the microphone and continued to reveal: "In addition to being self-reliant and self-reliant, I also hope that you can learn from his humble character and treat others with sincerity. You may not believe it when you say it. The ticket to this speech is the notepad cover you took. Every word on it was written by Du Qiu with one stroke and one stroke..."

"Wow! Did he write such beautiful words himself?"

"This young man is not simple. Not only did he teach programming by himself, but he even wrote calligraphy so well. I don't know where Lao Chen found it."

"Teacher Hou, how do you think this word is written?"

"I don't understand calligraphy, but it is rare for young people in their twenties to write such words."

Chen Zhiyang felt that the scene was almost warmed up, so he handed over the microphone to Du Qiu. He patted his back with the attitude of an elder and a junior, and reminded him: "Talk well, speak relaxedly, don't be nervous."

"I will."

Du Qiu walked to the center of the podium, stood in front of the multimedia platform with a laptop, preparing to give a technical speech. Before opening the PPT document, he cleared it up: "Principal Chen is too good. I don't have any excellent qualities worth learning. I just eat and wear warm clothes, and I made something that I am interested in. In essence, it is no different from those dandy who walk birds and cocks. So don't fantasize about other people's hardships to move themselves. It's meaningless and boring."

In 2016, chicken soup articles were rampant, so many people were disgusted. However, 1995 was the era when "Chicken Soup in the Heart" was just beginning to become popular. These words were not only inappropriate, but also a bit out of the ordinary, which suddenly dispelled the warm atmosphere that Chen Zhiyang had just set off, and a buzzing discussion appeared in the hall.

Du Qiu ignored it and continued, "Before the speech, I want to declare three things. First, applause and noise are prohibited, but you can communicate quietly without affecting others; second, if you have any questions, you must raise your hand first, and I agree before asking questions; third, if you have something or don't want to listen, you can leave through the front or back door, and don't disturb others when you leave."

He looked around the hall and paused for a few seconds. After the whispering voices disappeared, he nodded on his own and said, "Since everyone doesn't object, then I'll start."

"Open source software is a concept I proposed. Principal Chen invited me to explain some relevant knowledge to you. I am honored and thanked him for his support and support... Content about the definition and protocol of open source software is boring. If you are interested, after the speech, you can go to Teacher Cai to get a printed brochure and take it back to read it yourself, so I won't go into details."

"Everyone here is either students or teachers, so today I will mainly talk to you about the benefits of open source software in teaching."

Du Qiudian opened the first PPT and projected the code on the promotional poster on the curtain behind it, saying: "This code is the standard answer in many C language textbooks in China, but it has the problem of time complexity and is absolutely impossible to use in actual software development. If you dare to write such code after you join the work, you will either be beaten to death by the boss or scolded by the customer..."

There were sporadic laughter in the hall, and Du Qiu ignored it and continued, "But how many of you have considered the complexity of time when you are studying?"

The laughter disappeared immediately.

"This code was posted on campus for 3 days, and many students gave optimization answers. Some used dynamic programming to save the intermediate items calculated before, and search them directly during the next calculation to avoid repeated calculations..."

Zhang Dongliang looked at the code on the curtain, touched Xiao Jialin gently, and whispered in a somewhat proud tone: "It's the same code we optimized."

"He said some people do this, and there should be other ways to optimize it."

Du Qiu clicked the screen again, switched to another optimization method, and then introduced: "Some students used a simpler method to calculate from top to bottom and use loops to achieve recursion..."

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

His annoyance was not over, and immediately became surprised, because Du Qiu showed another optimization solution, which had a long code, but greatly reduced the time complexity from O(n) to O(logn).

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

"I can't understand either."

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

He first introduced a matrix formula, and then explained the code. The explanation was very concise. Zhang Dongliang was not very good at math and did not understand it. He said in some confusion: "It's just a Fibonacci sequence. Is it necessary to be so complicated?"

Xiao Jialin felt that Du Qiu must have other profound meanings, so he remained silent and did not answer.

Sure enough, after Du Qiu finished explaining, he said: "You may think that this optimization method is a big deal, and you are full. In fact, this formula can be used in other places and can be used to play a role in other places, such as calculating the power of integers of a numerical value. I will give you 10 minutes to this question, and think about how to program it."

Zhang Dongliang looked up and saw a question on the curtain, which was a bit similar to the one on the bookmark. They were designed to implement the functions of a certain library function in C language. It was also a problem that seemed simple at first glance but was very complicated to think about it. He took out his pencil, leaned against the cool wall, and smeared it on the notepad for several minutes, but felt his brain was messy and had no idea at all.

Du Qiu did not stand stupidly on the podium, but walked down the podium. 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 outstanding strength. Because the third optimization method is very remote and complicated, he used advanced mathematics knowledge. Not only did the students not expect it, but the teachers and professors did not expect that no one would neglect if he had the strength. They were all very enthusiastic, some encouraged and some praised it. Only Academician Hou was dissatisfied and said, "Xiao Du, you took Dayou to work in the United States and gave me a good student. Should I make a statement?"

“What expression do you want?”

"I like playing chess, but there are no suitable chess friends in the institute. Dayou said before that he would help me write a program that can play chess with computers. He has not finished it after half a year of writing. Why don't you write one for me? If you write it well, our grudges will be eliminated."

"Okay, then just say it's a matter of determination."

"It must be explained in advance that if the program you wrote is a bad chess game, I will not recognize it."

"Not guaranteed."

Du Qiu chatted for a while, and after Jiang Danfeng made the hint that 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 could come in to listen to the speech were not bad, so many people raised their hands. Du Qiu randomly selected a few students and asked them to hand over the answers, but they did not announce the correct or wrong. Instead, they switched the PPT document and explained the two codes he wrote. The first paragraph used traditional methods to solve the problem, and the code was dozens of lines, which were complicated and inefficient. The second paragraph used the mathematical formula just now to solve the problem, and the code was only a few lines, which was concise and efficient.

After the explanation, Du Qiu recalled 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 in learning programming."

"First, the knowledge in textbooks and the demand in production are two different things. Computers are productivity tools, not toys for talking about things on paper. It is not enough to only understand theory but not practice. However, with the current domestic environment, it is difficult for students to actually develop a mature commercial software. If you don't want to be a nerd, the only way is to read excellent open source software code and understand what real software development looks like."

"Secondly, computer software is an industry that emphasizes innovation. If you want to innovate, you must first accumulate. Literature 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, what kind of accumulation is that programmers rely on? Only by looking at the code of open source software, such as this formula, is what I discovered from the recursive functions of an 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 know that I would post these answers on the wall for everyone to see, will you think more rigorously? Write more carefully? If many people point out the mistakes in public, will you reflect seriously? Don't make the same mistakes again?"

These three benefits are very simple, and even the students present can figure it out. However, after these days of personal experience, everyone has a deeper understanding and understanding. The lecture hall is silent, and many people have a thoughtful expression on their faces.

Next, Du Qiu switched PPT to the title on the bookmark and explained it. Xiao Jialin only heard a few sentences and sighed: "No wonder Mr. Du said that I was barely considered a qualified coder. We did not consider the judgment and overflow of the maximum positive integer and the minimum negative integer."

Zhang Dongliang nodded silently and said, "In fact, few people thought of this omission."

"The software is becoming more and more complex now. Dozens or even hundreds of employees have become the norm. What software companies need are talents with teamwork, rather than single-handed heroes. If you do not have good programming habits and consider problems, you will patch them here and bug them there. Not only will the boss beat you up, but your colleagues will also smash you with the keyboard."

"This question on the bookmark is to tell you another advantage of open source software, which is to broaden your horizons, distinguish between good and bad, and distinguish which are good and bad programming habits, because many open source software are projects that strangers work together with each other. If the programming habits are not good, it is difficult to cooperate with others."

Du Qiu said this and 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 any comments, but I can tell you responsibly that after you complete one or read several excellent open source software codes, if you cannot find more than 200 errors, omissions or fallacies from this book, you are not a qualified computer major, because the programming thinking, programming style and programming habits shown in this book are extremely bad!"
Chapter completed!