Qiao Yu didn't want to get a good result in the preliminaries. He would be satisfied as long as he crossed the line, because according to the rules of the competition, the results in the preliminaries had nothing to do with the results in the finals.
But when the time came and he opened the question bank, Qiao Yu smiled.
For example, the first question belongs to the category of combinatorial geometry. One question tests plane geometry, combinatorial mathematics, visibility diagrams, etc. The question mentions the problem of line of sight obstruction, which is a metaphor for Qiao's understanding of mathematics.
The problem usually arises in computational geometry.
But this is a multiple choice question.
It's not like Qiao Yu is bragging. What he is best at is multiple-choice questions.
He didn't even need to draw a picture, just by clicking on the pre-arrangement and visibility questions, he deduced that the number of people could not exceed 6, and eliminated answer D.
In addition, the two towers E and F are not in sight, and then all you need to do is draw a picture in your mind according to the conditions.
In the end, the answer was exactly six people.
It took ten minutes and he felt very good. Qiao Yu looked at the second question, which was composed of two multiple-choice questions.
Coincidentally, this question examines probability theory and expected value.
It happens to be a field that he is familiar with. The mathematical idea that needs to be used in the first question is probably the memorylessness of exponential distribution. In layman's terms, it means that the probability of events in the future has nothing to do with the past.
In short, I have learned it and it is simple.
By the third question, Qiao Yu finally felt that it was starting to become more difficult.
However, this question tests the contents of algebraic number theory and geometric number theory, combining eigenvalues ​​and number theory. Qiao Yu finally understood the significance of the open-book exam. Discussing the density of grid points in the plane, he
I have some vague impressions in my mind, but I'm not sure.
So Qiao Yu started searching the Internet according to the prompts at the bottom of the question, and soon found the famous Minkovsky theorem. Then he started looking for various explanations of geometric number theory on video websites, marked them, and collected them directly.
However, Qiao Yu did not watch those videos for the time being. Instead, he gave up on the third question and started studying the following questions.
It's just a preliminary round. It's enough to advance to the finals. According to the situation in previous years, you don't need to complete all the test questions.
In this way, Qiao Yu spent the entire Saturday sitting in front of the computer answering questions, except when Qiao Xi called him to eat.
Xia Keke came to see Qiao Yu once in the evening as usual, but after learning that Qiao Yu was participating in an online mathematics competition, she did not knock on the door to disturb him.
There were seven questions in total. When Qiao Yu felt dizzy and went to wash up and go to bed, he had completely answered three questions. The first, second, and fourth questions.
The fourth question is about linear algebra and abstract algebra. It mainly tests the analysis of eigenvalue decomposition and eigenspace structure. This question is terrible for Qiao Yuqiang. Previous similar preliminary questions could not stump him at all, let alone him during this period.
I also strengthened my study of many algebra and number theory contents.
For the other four questions, Qiao Yu was not sure, or only had a rough idea, so he decided to wait until the next day to watch the video and answer two selective questions.
According to the experience shared by the finalists in the preliminaries in previous years on the forum, basically as long as you have the confidence to answer four questions correctly, you will basically get the ticket to the finals.
Of course, for the sake of safety, Qiao Yu decided to answer at least three to four questions tomorrow. You don’t have to be completely correct, but you should be able to get some points if you convey the general idea.
In addition, the reason why I am not in a hurry to do it today is that any operation online will leave traces.
Especially if you use someone else's backend and do a few questions a day, it will be easier to lose sight of everyone.
There is no money to be paid in the preliminaries, so there is no need to show anything special. After all, he is only fifteen years old, and there is almost no threshold for the Alibaba mathematics competition. This means that as long as the heart is strong enough and not afraid of embarrassment, mathematics professors from top universities People, even Fields Medal winners can sign up.
And he is just a little Karami who is just over fifteen years old.
If you are noticed because of your good performance, you might be put under the spotlight and observed.
Qiao Yu doesn't mind being famous, but according to this year's competition system, the results will be announced at the end of June. After allowing the players to prepare a little, the finals will begin in early July. During this time, people will be watching and talking about it, and there is no money. Ke Na is purely looking for trouble for himself.
To put it bluntly, the focus is still on the finals.
Qiao Yu climbed out of bed at six o'clock the next morning. He started watching the videos he had marked online yesterday and spent the whole morning studying. Qiao Xi brought him meals to his room.
It wasn't until two o'clock in the afternoon that Qiao Yu started answering questions again. At eleven o'clock in the evening, nine hours before the end of the competition, all the questions were completed.
It could have been done earlier, but the online question-answering system of Little Libaba is not that easy to use.
After overcoming this small difficulty, Qiao Yu is still very confident about reaching the finals.
…
Monday was the Dragon Boat Festival, a day off, but Lang Jie got up early in the morning, turned on the computer at eight o'clock on time, and started paying attention to the question bank of the Little Libaba World Mathematics Competition.
According to the practice of previous years, whether it is the preliminaries or the finals, Little Libaba will simultaneously publish the questions and answers in the historical question bank on the official website after the competition.
Although Mr. Olympiad does not need to study such competition topics and he has not signed up to participate in the competition, because the topics of the Little Libaba Mathematics Competition are very interesting, Lang Jie pays attention to them every year.
People who have no interest in mathematics at all may find it difficult to understand the feeling of relief after solving a difficult problem. Not to mention that Qiao Yu may also have signed up to participate in this year's competition. Lang Jie has always been curious about Qiao Yu's mathematics level.
Combined with the difficulty of the questions and Qiao Yu's score at the end, you can probably have an idea.
This year's preliminaries were arranged well. After the exam, it happened to be the Dragon Boat Festival break. He, an older single man with few other hobbies, could use it to study the test questions.
After reading it once, Lan Jie had a rough judgment in his mind. The difficulty was basically the same as in previous years, and it was probably at an intermediate or high level in the mathematics world. It also covered a wide range of topics, including algebra, geometry, number theory, combinatorial mathematics, and probability. Multiple fields.
This question setting mode is more friendly to contestants who come from mathematics classes. After all, these contestants have relatively systematic learning experience. It is indeed more difficult for non-professional contestants.
Especially the last question, which not only involves the modeling and solution of differential equations, but also includes the analysis of dynamic systems and the understanding and reasoning of periodic motion. It would have taken him a whole day to do this question, and It may not be possible to get it right.
As for Qiao Yu...
When the image of this child appeared in his mind, and when he thought of his pious attitude when he asked whether the bonus needed to be tax-deducted, Lan Jie was really not sure whether this kid could pass the preliminaries.
It's a pity that we have a day off today, so the afternoon Olympiad class has naturally been cancelled.
Chapter completed!