Just turned over a new leaf and became a wise and intelligent student

Chapter 234: Speed ​​of Life and Death! Race against time! (4k)

“I haven’t tried it.”

Xu Qingshan said with a smile.

"But I just happened to be warming up and practicing before the game."

Seeing Mei Hong’s depressed and confused face, Xu Qingshan comforted him.

"Teacher Mei, think about it, I have never tried a competition before. I have to wait until the day of the competition to get used to it. Why not practice tonight?"

"If I can do it, then you'll feel more at ease, right? If I can't do it, then it doesn't matter who I go with."

Xu Qingshan said easily.

"I've seen the ICPC schedule. It also requires a whole day of competition from morning till night. I've also gotten familiar with the schedule in advance. Teacher Mei, I'm leaving now. I'll go back and finish my work early and go to bed early. Bye."

Mei Hong looked at Xu Qingshan walking away, wanting to say something but stopping herself from speaking.

It was not until Xu Qingshan disappeared around the corner that Mei Hong let out a long sigh.

He still felt that this matter was unreliable.

If Xu Qingshan wants to rank in the top eight in the latest question bank rankings on the OJ platform, it means that he needs to complete 7 programming questions within and a half hours.

This isn't even a concept, okay?

To know.

Generally speaking, the total number of questions in an ACM competition is 8-12, usually 10 questions. If you can answer more than 6 questions, you will be eligible for ranking. The competition takes 5 hours.

That is to say, each question needs to be read, conceived, solved, verified and revised, with the standard of 1 minutes per question.

The reason why the first place in the 7-question ranking on the school's OJ platform took 12 hours, 46 minutes and seconds to complete the questions is because these people did not answer the questions continuously.

For example, Chen Fangping, who ranked first, had a total time of more than 432 minutes, with an average time of more than 4 minutes per question.

How is it possible to answer questions at such an absurdly fast speed?

First, Chen Fangping would choose a relatively free weekend and set aside special time for answering questions. Then, he would take a shower, turn on the air conditioner, ensure that he was in the most comfortable temperature environment, fill a cup of warm water, sit in front of the computer and meditate for ten minutes. After ensuring the best condition, he would simulate and practice quick solution ideas for various types of questions in his mind, and then start answering questions.

The question bank of the OJ platform is distributed according to difficulty levels.

The first 40 questions are of easy difficulty, the middle 30 questions are of medium difficulty, the last 20 questions are of difficult difficulty, and the last 10 questions are of competition difficulty.

Almost every half an hour, Chen Fangping would stop answering questions, log out of the webpage, and continue meditating to adjust his state.

Just like the first 40 questions, he almost typed quickly on the keyboard while looking at the questions. Normally, he could give accurate and concise answers and submit them within a minute after reading the questions.

This requires strong programming skills and practical proficiency.

Basically, these experts who are able to stay at the forefront on the Peking University OJ platform can complete the first 70 questions within 2 hours, spend 2 hours on difficult questions, and spend the remaining 3-4 hours working hard on the last 10 questions.

This also corresponds exactly to the 20 to 30 minutes to solve each question in the ordinary ACM competition.

Of course, the solution here is just a solution, which does not mean that there will be no errors or the whole question will be wrong.

Like Chen Fangping, in fact, some people in the Institute of Information Science and Technology have already called him OJ Senior Brother and OJ Phantom God.

Because the OJ platform does not have a fixed ranking, but will update the question bank, just like an e-sports competition will enter a new season and players can join the battle. The OJ rankings mentioned by normal students of the School of Information Science and Technology are referring to the rankings of the latest question bank.

But no matter how the OJ question bank is updated, Chen Fangping has been ranked first in the OJ rankings for the past two years since he achieved enlightenment in his second doctoral degree.

As soon as a new question bank comes out, he will start to work through it as quickly as possible.

And because the question bank is based on difficulty, his time always starts with 7, and it seems that he is about to squeeze it under 7 hours.

This record is difficult to break for students in school.

but
In fact, there are quite a few people in Huaqing next door who can break 7.

At least as many as one palm.

Although the OJ question banks of the two schools are not exactly the same, the difficulty coefficient is even higher than that of Huaqing. In this case, there is still such a gap in speed, which is enough to show the gap between Peking University and Huaqing in the field of programming.

Xu Qingshan returned home. There was no class in the evening, so Jiang Huanxi went back to the dormitory tonight.

It’s not good if you don’t live in the dormitory all the time.

Even though Jiang Huanxi was a novice, she would always be intermittently sober and feel ashamed.

"Yang Shu said he could be number one, and it seems like he wasn't just bragging."

Xu Qingshan has logged into the OJ website platform according to the process Mei Hong sent him, and is looking at the latest ranking of the question bank.

Yang Shu completed 98 questions in just 6 hours and 11 minutes.

If he could finish the last two questions within 1 hour, he could indeed surpass Chen Fangping.

But even so, Xu Qingshan is very confident.

In fact, his programming level is higher than Mei Hong imagined.

The main reason was that during the period when he was self-studying in Ludao, he mastered things very quickly. His strong memory and his brain, which had been continuously developed through his own learning, produced inspiration at an unimaginable speed.

If Xu Qingshan were to evaluate himself.

When I was just reborn, my brain power level was 1, and it has almost increased to 3 in the first half of this year.

During the summer vacation, the more I came into contact with cutting-edge technology and the more in-depth development I went into, the more problems I encountered and the more thoughts I had.

Today, his brain power index can be described as 10.

And he also realized that this did not seem to be the limit of his growth.

At present, there are some pioneering problems that are beyond the scope of experience. If he wants to make a breakthrough, he needs an unintentional reminder from others to break the hazy boundaries of inspiration.

But if one day your brain is trained to the extreme, will you be able to solve many difficult problems at development nodes without any guidance?
Xu Qingshan gave himself a positive answer.

After taking a quick look at the OJ rankings for a while, Xu Qingshan found exercises of various levels to practice with, and then he had a general idea in his mind and was ready to start this extreme challenge.

【start】

【19:27:09】

Xu Qingshan clicked the start button with great concentration. As soon as the page was refreshed, he quickly read the question information. While reading, his hands had already started entering the code in the answer box.

In fact, there are some skills to doing this kind of OJ question bank.

Xu Qingshan mastered this test-taking technique in the first place, and it was completely applicable to both simple and medium-level questions.

The first thing is to look at the question and determine the keywords, and then instantly derive the directional category from the keywords. Then you can use both hands to input the front frame of this code, and then think about the problem-solving process while answering the questions.

In this way, Xu Qingshan is confident that he can answer simple questions within 1 minute!

[Delete node], [Link list], [fixed value val]

Xu Qingshan's eyes captured the key words at the first moment.

[typedef struct ListNode List Node; newline; struct]

Xu Qingshan's hands almost left afterimages.

Moreover, with such a fast blind typing speed, there was not a single mistake in any letters. After Xu Qingshan finished reading the question and checked it again, he had already solved it. He scanned it with his eyes and solved the problem within 20 lines.

Use the simplest while loop statement and double if, assign the first node that meets the conditions as the head node to the new initial node, and then connect the nodes that meet the conditions in series after the initial node to complete the new linked list.

【submit】

【Inspection and testing】

【Test passed】

When the green check mark lit up, Xu Qingshan felt relaxed and relaxed, and glanced at the time again.

【19:28:04】55 seconds.

This is also thanks to the fast computer refresh speed, fast internet speed, and even faster typing speed.

Otherwise it will take at least 1 minute.

Xu Qingshan did not get complacent with his success on one question. He no longer paid attention to the time, but quickly scanned the OJ question bank.

Maybe it's because things are getting better, or maybe it's because the battle is so exciting.

Xu Qingshan's hands moved faster and faster, and his eyes moved faster and faster.

Time passes minute by minute.

At the top of the OJ website platform, the nodes that continuously move from left to right represent the progress of Xu Qingshan's answers.

So far, 67 questions, all green! All correct!
It took 1 hour, 33 minutes and 36 seconds!
In order to better calculate students' scores, the OJ platform of Peking University has a corresponding time point at each node, which will be displayed after clicking on the specific question.

At this time, Xu Qingshan was still answering questions quickly. If he clicked on his difficulty change node, he would find out.

For the first 40 simple questions, Xu Qingshan answered them in an astonishing 38 minutes.

I truly achieved an average speed of 1 minute per question.

If it is a search engine, sometimes it may not be able to find the exact original question in 1 minute.

As for the medium-difficulty questions, Xu Qingshan also progressed quickly, at a speed of 2 minutes per question.

Although normally, the most optimized and concise answers for simple and medium difficulty questions should be around 10-30 lines of code, and the speed of inputting a line of short code for a skilled top programmer is as fast as 2 seconds and as slow as 5 seconds.

This means that Xu Qingshan has been maintaining the normal human strength for one and a half hours.

In fact, it should not be called an ordinary person.

Programmers who can reach this level will be top bosses wherever they go.

Fortunately, it was time for the difficult questions.

The number of lines of code required did not increase too much at one time, and it was more of a test of programming thinking, so Xu Qingshan's hands were able to rest for a while and his brain continued to lead the way.

For a normal expert, the average time spent on 20 difficult questions will be more than 7 minutes.

A master who is famous in Huaqing University and Peking University may be able to sprint past 5 minutes.

But Xu Qingshan only took 4 minutes.

As we all know, Xu Qingshan's brain is stronger than his body.

What limited his speed in solving the previous simple and medium questions was not his brain power but his hand speed.

The further it gets, the more Xu Qingshan gets to indulge himself.

There are 20 difficult questions with different difficulty categories, and long codes and multi-line answers begin to appear frequently.

许青山没能每题都控制在4分钟左右，最后20道题的总时间花了1小时35分钟57秒。

As of now, Xu Qingshan only has the last 10 competition-level questions left.

And it only took him 3 hours, 9 minutes and 33 seconds!
This speed is amazing.

Even on the current ranking of the new question bank on Huaqing University's OJ platform, with the same 6 questions and the same difficulty distribution, the top place from Huaqing still needed 24 hours, 45 minutes and seconds to complete and answer all the questions correctly.

If Xu Qingshan not only wanted to surpass the first place in Peking University, but also wanted to surpass the first place in Huaqing University.

Then spending 20 minutes on each competition-level problem is not enough.

Simply put, Huaqing's first time is 23085 seconds, and Xu Qingshan's remaining available time is 11712 seconds.

He must control the average time for each question within 19 minutes and 31 seconds!
Every second counts!

And if the gap was just that small, it would be hard for Xu Qingshan to proudly say that he was stronger than Huaqing No. 1.

Because Huaqing’s question bank is slightly more difficult than that of Peking University.

Even if the difficulty coefficient increases by only 0.01, if the duration cannot be extended, Xu Qingshan will only feel that he has lost.

Without relaxing, Xu Qingshan just paused to drink a sip of water, went to the toilet to meet his physiological needs, and then immediately returned to the computer.

【22:38:25】

Xu Qingshan rested for more than a minute and then immediately started fighting again.

【Problem 1: Multiplication of large numbers. 】

[Problem description: Program to multiply two arbitrarily large integers with a number of digits not exceeding 300. ]

Xu Qingshan's eyes moved, but this time he did not rashly write code. Instead, his eyes kept flickering, and after a moment, his hands flew on the keyboard again.

This question is relatively easy to answer among the competition questions. The idea is clear. Let’s get started!
【22:54:47】

【Test passed】

next question!
Xu Qingshan has completely entered that extremely excited flow state.

The first 90 questions were like a warm-up match for him.

Now comes the real challenge.

only.

These competition questions, which would be a headache for ordinary computer students, seemed so easy in Xu Qingshan's eyes.

His hands tapped the keys as if he were playing a piano.

And the music they played was of a rhythm similar to "Flight of the Bumblebee" and "Croatian Rhapsody".

【23:10:54】

【23:29:04】

【01:41:32】

【Test success】

【All completed】

【总用时：06：14：23，正确率：100%，OJ排行榜排名：1】

"Snapped!"

As Xu Qingshan pressed the last enter key.

The Enter key of the Double Flying Swallow keyboard that I bought temporarily was sunk in and got stuck.

“Is this keyboard really that broken?”

Xu Qingshan was a little puzzled.

I was typing a little too fast just now, especially the big Enter key, I don't know how many times I hit it, but aren't these two Feiyan keys famous for their durability?
I reached out and fiddled with it, and finally got the Enter key out. It still works.

Xu Qingshan breathed a sigh of relief.

The tension of Speed ​​is not as great as worrying about the keyboard breaking.

But after relaxing, Xu Qingshan looked at the ranking list of the new OJ question bank of Beijing University in front of him and saw that everyone's name had moved down one place, and his name appeared in the second row. He felt a sense of accomplishment.

Why not the first line?
Because the first line is basic information: name, number of questions completed, number of correct questions, time taken to answer the questions, etc.

I have to close the chapter tonight! I will get up, put away the cat and start coding!

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(End of this chapter)