On the morning of July 3, Tsinghua Second Teaching Building.

Second Church is an old building built before 1949.

It is rumored that the Second Sect often encounters supernatural events, commonly known as haunted.

The second education is never open at night, and the school says it is to save water and electricity.

The highest scientific research and academic institutions like Tsinghua naturally advocate science. The monsters and monsters can only have a shattered fate in the face of powerful scientific power, and they are not allowed to become spirits after the founding of the People's Republic of China.

At this time, more than half of college students completed the final exams, and the second class was empty. This is the national preparatory and national finals of this year's High School Mathematics League.

National preparatory will be held at exactly 9:00 this morning.

There is still half an hour left to start the competition, and a total of 192 players from 32 provinces and cities are on standby in 201 and 202. A total of 60 of them will be qualified for the national finals.

"Actually, I'm very satisfied to be able to participate in the national competition, really." said Qi Jianhong, the youngest player in the Guangdong Provincial Number Competition Team.

Shen Qi scolded: "Qi Jianhong, you know nothing. If you can't enter the national finals, we're just going to Tsinghua University in vain. Do you think you are a member of the five tyrants of Hubei, Hunan, Zhejiang, Beijing, and Shanghai. If you are selected as the provincial team, you can get the signing of Tsinghua and Peking University?"

Qi Jianhong was dissatisfied: "I don't rely on the admission to the college entrance examination. Can I get into Tsinghua and Peking University?"

Shen Qi asked: "You have good grades in other subjects?"

Qi Jianhong said proudly: "That's, in our high school, I have long been the first in the whole grade. If I can't get out of the second place, I will lose by scores above 50. Mathematics is just my hobby. I rely on my invincible comprehensive strength to dominate the whole grade."

"You little boy is quite awesome, but I don't care how awesome you are in your high school. This time, you must give me the highest level of your national preparatory exam, otherwise I will hit you." Shen Qi said resolutely.

"You, you... are so barbaric!" Qi Jianhong was only about 1.5 meters tall, and he had no power to tie a chicken. He would definitely not be able to beat Shen Qi who was about 1.7 meters tall.

"Actually, what can I do if I beat you? From the start of the training camp, I repeatedly emphasized that we are the same team, from the same place, and have a common dream. I can't beat you five by myself, but I have a heart of a champion. And you are all hot." After Shen Qi finished speaking, he left the 202 classroom with his stationery suit without looking back.

"Shen Qi, you... you actually said we are hot chickens!" Qi Jianhong was both ashamed and annoyed. He said to the other four teammates: "Shen Qi said we are hot chickens, it's so hateful!"

"Hmph, Shen Qi is this pretender."

"We are not spicy chickens, we are strong people!"

"Shen Qi, soul is calm, I must defeat you!"

"I must have higher exams than you!"

“+1!”

Qi Jianhong and the other five people shared the same hatred of the enemy, and an unprecedented atmosphere of unity appeared in this team for the first time.

Shen Qi, Qi Jianhong and six others were arranged in six different classrooms, with a 9-point spread of 5 points, and the invigilator began to read out the competition rules: "The rules are very simple. You have 3 hours to complete the national preliminaries. You must not look around during the answering questions. If you have any questions, please raise your hand. After the competition rules are read out, the test paper and draft paper will be distributed below."

Shen Qi took the exam in Classroom 101. He got the national preliminaries and quickly browsed the three test questions, each with seven points and the paper score was 21 points.

From the provincial preliminaries to the provincial rematch, and then to the national preliminaries, the scores of the paper are getting lower and lower, but the difficulty is getting higher and higher.

In the first question, a pattern was drawn on the paper.

There are two small islands floating in a river, with bridges connected between the islands and bridges connected between the islands and river banks.

There are one river, two islands and eight bridges in total.

Question: How can a walker walk through eight bridges in one go without repeating them and finally return to the starting point.

"Hey, who did this question? What would Euler allow you to do this?"

Shen Qi saw through everything at a glance. This question is a variant of "Ola Seven Bridges", Tsinghua Eight Bridges?

Euler, a god-level master in the history of mathematics, was very energetic when he was young. He liked mathematics and girls.

When Euler was in her twenties, she fell in love with a girl, a beautiful and gentle art teacher. He pursued this art teacher frantically and finally achieved success. The two got married and gave birth to 13 children... It can be seen that Euler is not only top academically, but also has a great body.

On a bright spring in 1736, Euler waited for his art teacher’s girlfriend to arrive in a park in Cornisburg.

Lateness is a woman's innate attribute. She waits around and waits. An hour has passed, and the girl who teaches art has not yet arrived.

Euler was bored, so he began to study mathematics. He found that two small islands were suspended in a river in the Cornisburg Park, and there were seven bridges connecting the island and the river bank. Visitors walked to the island through the bridge to relax and shuttled between the two small islands.

Euler suddenly had inspiration and proposed a vision of whether there is a path that can be left out from any place without missing out, pass through the seven bridges without repeated repetition, and finally return to the starting point.

Later, Euler wrote this idea into a paper and submitted it to the St. Petersburg Academy of Sciences. The paper was titled "Seven Bridges in Cornisburg". Later generations also called it "Seven Bridges in Euler".

Later, Euler overturned this assumption himself and proved that such a path could not exist.

In order to slap himself in the face, Euler invented a new method of proof, and he created a new branch of mathematics - geometric topology.

This is the pattern of top mathematicians. I am invincible and I have no opponents. My only opponent is myself. In order to defeat myself, I have created a new branch of mathematics.

Two or three hundred years have passed, and Shen Qi is facing a new problem, the Baqiao problem.

The original version of the Euler Seven Bridge was unable to get the answer. As for whether there is such a path to the Eight Bridge, you have to calculate it before you know it.

Shen Qi calculated from the top and bottom, left and right, half an hour passed, and it couldn’t be calculated!

Whether the Eight Bridge is the same as the Seventh Bridge, there is no so-called path at all. It can pass through each bridge without missing out and repeating it, and finally return to the starting point.

"After all, the national competition is a national competition. Topology is very difficult to deal with. I can't find this path, nor can I prove that it does not exist."

Shen Qi put down the pen ruler and pressed the temple vigorously. It was not good for him to go out, but it was not good for him to go out.

Time passed by minute by minute, and Shen Qi was unable to write. He had a bit of obsessive-compulsive disorder and had to solve the first question and then solve the next two questions.

"Ola, Seven Bridges, Eight Bridges... By the way, why do I have to use Euler's theory to solve the variant problem based on Euler's seven bridges? This is a trap, a dead cycle!"

Shen Qi suddenly realized that I thought of it, I thought of it, Poincaré’s network theory!

If the two broken ends are exactly the same as before, this is a permissible topological operation.

Otherwise, it is not allowed!

That's right, the singularity of the eight bridge diagram is at both ends, so there is no such connection at all. It can pass through each bridge without missing out and repeating it.

The answer to this question is: No! Exist! It’s there!

Shen Qi wrote down the proof process quickly, and he completed the proof in just 3 minutes, while the thinking process lasted for 1 hour.

"Huh... I got the next question, the next question." Shen Qi let out a long sigh, burning many brain cells to death, so tired. But the battle had just begun, and he could not relax. He had to complete all the answers within the specified time and ensure that they were absolutely correct.
Chapter completed!