Xueba, I beg you to go and escort him quickly!

"@许宗云, just cry! You found the question with great difficulty, but Xu Heng gave the answer directly!"

"I feel sorry for Xu Zongyun for a second!"

"Distressed for three seconds!"

"My heart hurts for five seconds!"

"..."

"Distressed for 1 minute!"

Xu Heng looked at the group news with a smile on his face.

Got it!

You guys do something about it!

If this trouble continues, they will definitely have to solve the problem.

Xu Heng was one step ahead and recorded directly, "First, color the position (x, y) according to the parity of x+y, and the two positions whose distance is 5 below the root sign are different colors."

"A keeps red stones in the position of one color, at least it can place red stones in the general position of this color..."

At first, the driver didn't understand why Xu Heng spoke.

But as he continued to listen, he immediately understood.

This Xu Heng is still studying in the car!

wrong!

To be precise, he also guides others to learn!

incredible!

Student Xu Heng!

No wonder the director asked me to pick you up in person!

driver,"!!!"

He put all his energy into driving for Xu Heng.

Xu Heng continued, "Extend this grouping to all positions of 20*20, each time A is in a certain position..."

"So in this way, B can ensure that A places one more red stone in each group."

After the recording was over, he sent the process in.

There is no chance for these guys to do things at all.

but--

Xu Heng still underestimated them.

To be precise, it was Xu Heng who underestimated Mr. Hong!

This old man is really an old urchin. He was the first to propose, "Since this question is so simple, student Xu Heng, please come up with one for everyone!"

"Actually, I will also do the question you asked!"

"I have been here for so many days, and they keep saying in my ears that your questions are good, so good, so good, I am really itchy!"

"As soon as I saw you talking in the group, I immediately went to the study to get a pen and paper, and I was just waiting for you to come up with a question."

As soon as Mr. Hong said these words, other people in the group followed: "Our paper and pens are also ready! Thank you, Xu Heng!"

"Our paper and pens are all ready! Thank you, Xu Heng!"

"Our paper and pens are all ready! Thank you, Xu Heng!"

"..."

Just refresh the screen!

Xu Heng, "%￥#@￥￥*..."

If Xu Heng said that he didn't have a pen and paper in the car, they would definitely think he was making an excuse.

never mind!

Xu Heng looked at the driver and asked, "Is there a pen and paper in the car?"

The driver pointed to the back, "Yes! Look behind you."

Xu Heng turned around, there really was behind him!

"Okay, thank you."

Picking up the pen and paper, Xu Heng frowned slightly. After thinking for more than ten seconds, he began to write.

topic:

There are n straight lines that are not parallel, and no three lines intersect at one point.

Their planes are divided into several regions, some of which are limited in size, which we call limited regions.

Proof: When n is sufficiently large, at least n straight lines under the root sign can be colored blue, and the boundaries of none of the finite regions are blue.

The topic comes as soon as it is said, and it is still the kind that makes people puzzled!

He is simply the big devil!

After finishing writing, Xu Heng sent the topic directly to the group.

The originally noisy group was instantly quiet.

Group owner @红景军, "Old Hong, let's see! Xu Heng's questions are so unique, I dare say, his question is very hot!"

Hong Jingjun was just about to type a reply.

Xu Heng's words have already been sent to the group, "@All Members, this question is also very simple, it only takes 15 minutes, and there are two solutions, so we won't wait until it's outdated."

"I'll post the answer in 15 minutes."

Treat others with their own way!

Xu Heng's move made everyone anxious and became ants on the hot pot.

……

PS: Thank you for the support of [Revel] [Presumptuousness] [Sigh of the Sky]! .

Chapter 278

Nima!

Nima! !

Nima! ! !

15 minutes?

There are two solutions?

"Master Xu Heng, you did it on purpose!"

Xu Heng, "Yes."

Everyone, "Puff——"

"@红景军! Help, Mr. Hong! Please help us!"

"We can't encourage Xu Hengda to be so arrogant!"

"Where there is oppression, there is resistance!"

"Master Xu Heng..."

"..."

Xu Heng, "You guys still have less than 14 minutes and 30 seconds left."

"14 points 29...28...27..."

Everyone, "!!!"

Everyone shut up, there was no one shouting, and they began to bury their heads and look at the questions frantically.

But where can their hearts be calm?

15 minutes to give the answer, and also asked for two solutions?

Is this what people do?

"Hey……"

Many people sighed, but Hong Jingjun chatted privately with Xu Heng.

"Student Xu Heng, you came up with these two questions cleverly!"

"However, you said that there are two ways of solving the problem. Are they pretty much the same, or... quite different?"

Xu Heng smiled, "Master Hong, you came to test me for them, right?"

This old guy is really good at tossing!

Hong Jingjun, "It's just a small fight with them, and you, I'm serious!"

"I have a special liking for mathematics. I finally waited for your question, and I was like a dry sponge that finally met water!"

"It's like a fish in water..."

Xu Heng, "Old man, you are with them for a while, and you blow my rainbow farts for a while, aren't you going too far!"

"Hahaha……"

Since Hong Jingjun is an old urchin, he won't get angry if he says something.

On the contrary, it is more cheerful.

"You little guy, interesting, really interesting."

"I'm not with anyone, I'm here just for math problems!"

"Live to be old, learn to be old! Teacher Xu, I ask you for the second way of solving problems!"

Xu Heng, "Old Hong, don't make fun of me with 18! With your ability, don't you know the second way to solve the problem?"

Hong Jingjun was embarrassed, "If you give me enough time, none of this will be a problem, but...you only gave me 15 minutes! I can think of the first one in this limited time, and perfect the first one. Very good!"

"As for the second one, I'm really too late."

Xu Heng, "Then what if I give you half an hour?"

Hong Jingjun, "You think highly of me too."

Xu Heng, "One hour?"

Hong Jingjun, "Ahem! Little guy, don't push yourself too far! You're going too far!"

"They're right, you little fellow, very bad."

Xu Heng can see that this old man is determined not to think for himself, he just wants his second way of thinking about solving problems.

It's just...you know the first kind, but you didn't tell me!

Xu Heng, "Old man, what's your thinking?"

Hong Jingjun really discussed with Xu Heng.

After all, this one can really be regarded as the leading figure in the domestic mathematics circle!

Red King Army, "Assuming that at most k of them can be dyed blue, so that no boundary of a limited area is a blue edge, then there are nk straight lines that have not been dyed, and dyeing any of them blue will make At least one limited area is bounded by blue borders."

"k blue lines intersect in pairs..."

Hong Jingjun roughly expressed his thoughts.

Xu Heng said, "This needs a lemma to prove."

Hong Jingjun, "That's right, it must be proved that the value of each blue dot is less than or equal to 2."