"Tsk, isn't this a vertical and horizontal diagram," Yuan Chang pouted, "We learned this in our math class, and I learned it so much." ”

The nine-square grid is said to have originated from the Hetu Luoshu, which is considered to be the source of Chinese civilization, and was known as the "cosmic Rubik's Cube" in later generations, and the ancient Chinese called it the "vertical and horizontal map", and later extended the game of rearranging the nine palaces, which was particularly popular in the Tang and Song dynasties.

The nine palaces played by the ancients usually only had nine squares in horizontal and vertical directions, requiring nine numbers from one to nine to be filled in the grid, so that the sum of the numbers in each column of the horizontal and vertical columns and the diagonal oblique column was equal to fifteen. At present, the nine-square grid on the stone table is 9x9 format, composed of nine 3x3 small nine-square grids, each 3x3 small nine-square grid is called a "palace", a total of nine "palaces", a total of eighty-one grids, Gerry has been carved twenty-one numbers, Yan Qi glanced at it a few times, see the picture as follows:

Eight □□□□□□□□

□□ three six □□□□□

□ 7□□9□2 □□

□ five□□□ seven □□□

□□□□ four, five, seven□□

□□□ one□□□ three □

□□ one□□□□ six eight

□□ □□□ □

□ □□□□ □□ four

Obviously, the rule requires that the numbers from one to nine be filled in the □, so that each row, each column, and each "house" contains the nine numbers from one to nine, and cannot be repeated. Interestingly, all the "□" are recessed in the table, except for the engraved numbers.

Who is so idle that grass grows on their heads, and carve such a problem that kills brain cells in such a place.

Yan Qi and Yuan Chang looked at each other and walked away, Yan Qi went to see the sentence in the scripture written with gold dust on the pavilion pillar, Yuan Chang jumped up and down and looked around aimlessly, and suddenly said: "Yo, there is a small drawer under this desktop." ”

As he spoke, he tore out the drawer, and saw a wooden box inside, and opened the lid of the box, and there were stacks of square and square wooden blocks with numbers engraved on them.

"No wonder the space on the desktop is concave," Yuan Chang took out a wooden block from the box and filled it into the depression of the nine-square grid on the desktop, "Look, it turned out to be to fill in the numbers on this wooden block! ”

This chessboard is really well done. Yan Qi walked over and took a look, and saw that Yuan Chang was pouring out all the wooden pieces in the box to fill in the hollow of the desktop with obsessive-compulsive disorder. After filling in a few pieces, I found a different kind of wood, the other blocks were made of pure wood, one side was engraved with numbers, and the back was a normal wood surface, and this piece of wood, one side was engraved with the number "nine", and the other side was embedded with a glass mirror. After examining all the wooden blocks, it was found that there were as many as seven such wooden blocks with mirrors embedded on the back, and all of them were embedded behind the number "nine".

"What do you think of this?" Yuan Chang asked Yan Qi.

"There must be something strange about this. "Yan Qidao.

"Strange fart, I think this person is just playing tricks. Yuan Chang randomly embedded all the wooden blocks into the lattice, and slapped his hand, "Let's go, go play elsewhere." ”

Yan Qi drilled the cave at noon, and he had no strength to train in the afternoon, and the whole person used to climb to get into the carriage home, Young Master Yan Jiu lowered his eyes and looked at his sister who was crawling at his feet, and lightly condoled: "How did you eat at noon?"

"I was wrong. His sister hugged his leg and cried blood and confessed her mistake.

"What are you playing with Yuan Chang at noon?" Young Master Yan Jiu used his toes to know what would happen to his sister following Yuan Chang.

"In and out of the hole, over and over again, he made me really weak, so he let me go. His sister said.

"...... "Shut up!" What the hell are you reading every day!

"I heard that you still learn math?" his sister revealed her ulterior knowledge by knowing that she had lost her mouth, and she was very blunt and naturally reversed the subject.

"Hmm. Young Master Yan Jiu put his gaze back on the page of the book in his hand, the title of the book was "The Ancient Arithmetic", and he was really learning mathematics.

"Do you want to learn Sudoku?" Yan Qi asked.

"What's that?" Young Master Yan Jiu put down the book and looked at Yan Qi's face, this thing always looked careless in other things, but this kind of academic thing was quite interesting.

Yan Qi took the pen and paper, usually the four treasures of the study room were prepared on the carriage and only used occasionally by Young Master Yan Jiu, dipped in ink, Yan Qi drew the nine-square grid Sudoku in the pavilion on the paper.

After successfully distracting his younger brother's attention, Yan Qiwei fell asleep in the car seat, tired, Wu Changge was really ruthless this time, and he couldn't wait to train her to the point where fat was spilling directly from the pores of her sweat. Not to mention that it worked, Yan Qi slept directly into the house, didn't eat dinner, struggled to write his homework and took a shower, and fell asleep as soon as his head touched the pillow.

When I got up the next morning, my bones were still aching, and when I sat in the carriage with a shy stomach, Young Master Yan Jiu handed her a piece of paper, and when I took it and looked at it, I saw that it was the cracked answer to the nine-square grid Sudoku yesterday. "That's good, how long did it take to solve it?" Yan Qi praised his younger brother.

"Half an hour. Young Master Yan Jiu said slowly.

"Awesome. Yan Qi continued to praise without any basis.

"Huh. Young Master Yan Jiu didn't say anything.

By the time he and Yuan Chang went to Zhiwei Zhai for lunch at noon, Yan Qi knew why Young Master Yan Jiu didn't smile anymore, "Yesterday's Jiugong Grid, I took it to our gentleman who taught mathematics to solve it, and today he told me that he solved it all night, and he hasn't solved it yet!" Yuan Chang said to Yan Qi with a mocking tone.

"......" Yan Qi's chopsticks were petrified for a while with Tian chicken leg stewed duck neck, "It's so difficult?"

"What do you think!" Yuan Chang snatched the duck neck from her chopsticks and said as he chewed, "Our husband said that the person who came up with this question is not a genius but also a genius, because this question, don't look at the eighty-one grids only gives twenty-one numbers, but in fact, its answer is very likely to be only one, that is, the remaining sixty numbers have only one arrangement-you say, is it difficult? Only the first grid at the top has a number, and the remaining eight spaces are not counted, how much time will it take you to touch all eight numbers!"

"It's hard. Yan Qi put down his chopsticks, because this dish was too disgusting.

"Our husband said he was going to show it to the other math teachers to see who could solve it. Yuan Chang pointed to Yan Qi's plate, "If you don't eat it, I'll eat it, my dishes are not enough." ”

"Don't eat leftovers, buy some more. "Yan Qidao.

"Where are you so exquisite, we men are not as disgusted as you women!" Yuan Chang said and snatched Yan Qi's plate, eating happily, as if it was some kind of human delicacy.

After eating, Yuan Chang said that he wanted to go to the pavilion to have a look, because maybe the person who asked the question would hide the correct answer nearby, so he flew over with Yan Qi again, and searched all over the pavilion, and even climbed to the top of the pavilion and turned it over.

Yan Qi stood at the stone table, took out Yan Xiaojiu's answer from his sleeve, and then sorted the wooden blocks embedded in the table according to the order of the numbers above, and finally admired it again, every horizontal, every vertical, every palace, none of the numbers from one to nine or nine were repeated, proper.

Yuan Chang jumped down from the top of the pavilion, and didn't notice that Yan Qi had changed the position of the wooden block, and only said: "I can't find the answer anywhere, maybe it's in those few wooden blocks with mirrors embedded in the back, why don't you knock it open and take a look." As he spoke, he found a wooden block with nine characters engraved on the table, and turned it over and was about to break it, but a little fat hand reached over to block it.

"Mirrors are used to reflect things, if the answer is hidden in wooden blocks, why should there be a mirror embedded in the back, instead of something else that can be used to make special marks?" Yan Qi took the wooden block in Yuan Chang's hand, turned it over, and put it back into the grid, "Since there is a mirror embedded in the back, I think it may be used to reflect things, so what if it is turned over with the mirror facing up?"

Yuan Chang probed to look at the seven mirrors, and then looked up, because the mirrors were all reflected on the top of the pavilion ornaments, the two of them looked up together for a long time, and the patterns on the top of the pavilion were ordinary folded osmanthus ornaments.

"Just to follow this?" Yuan Chang looked at Yan Qi.

"It's beautiful. Yan Qi said.

"It doesn't make sense. Yuan Chang knocked on Yan Qi's skull, pulled out a mirror, and kept adjusting the angle in his hand, looking at the surrounding scenery indiscriminately, "But one thing you said is right, there must be some idea in the embedded mirror, otherwise why not inlay copper and iron inlaid glass? What else can this mirror do besides the scene?"

You can only look at the scene, otherwise what else can you do, could it be to take a picture of the demon? Yan Qi tilted his head, and the mirror on the table changed the light and shadow due to different angles.

Light?

In addition to reflecting the scene, the mirror can also reflect the light.

But this pavilion is in the shade of the rockery, even if it is noon now, the light can not shine here, where to reflect it?

However, the angle of the sun is also constantly changing, maybe at a certain time, its light can just shine through, but Yuan Chang and Yan Qi are not so painful that they can stay here for a day and wait for the sun to shine, so the two of them decided that we should go drill holes.

Jumping back from the pavilion to the rockery, Yan Qi glanced back, and then was stunned: Nima, this hint is too straightforward and rude! The person who asked the question must be not wrong with the snake spirit disease, the first pavilion of Youchu, the first moment of the unitary time, the sun sets in the west, this angle is very likely.

"Let's take a look at it at the beginning. Yan Qi and Yuan Chang said.

"Okay!" Yuan Chang was very happy, this was the first time Yan Xiaopang took the initiative to ask him.

However, the club activities in the fourth class in the afternoon started from the whole hour, and Yan Qi was not ready to be fat enough to dare to challenge Wu Changge's authority and skip class again.

"Silly, when the time comes, I will use light skills to take you over, it won't take long to come and go, if Wu Changge asks, you will say that you will have to run your stomach. "Yuan Chang gave Yan seven tricks.

This excuse is really good.

Later, Yan Qi acted according to the plan, and met with Yuan Chang in a place where Wu Changge's sight could not be scanned, and then Yuan Chang carried her all the way to the Youchu Pavilion.

When they arrived at the Youchu Pavilion, the two remembered that the four seasons are different, and the height of the sun at the same time is also different.

"Since you're here, I'll have to wait a little longer. Yuan Chang said very simply, "The sun has just begun to sink in the west, and I don't think I will wait too long." ”

Just wait, I'm struggling anyway. Yan Qi has always been good, so he is not in a hurry.

As the sun shifted, the light swept over the high and low sloping rocks, and there was a brilliant but not dazzling light, passing through the mountain through the pavilion, and sprinkled lightly and warmly on the stone table. The seven small mirrors received this light and gently refracted it, and following the pillar of light, Yan Qi Tongyuanchang's gaze fell on the scriptures written in gold powder on the red pavilion pillar.

Seven small mirrors, shining on seven different characters on different pavilion pillars.

However, there are other words around these seven words, and the angle at which the sun sets in the west is different, and the words pointed by the pillar of light must also be different, so how can we determine that these seven words are the real target pointed by the small mirror? If after a while, the pillar of light moves away, and it will point to another seven words, and which seven words will prevail at that time?

For this reason, the two stayed in the pavilion for a while, and then dispelled the above doubts, the original scripture font arrangement on the column, in order to look beautiful, when writing, there are big and small, fat and thin, and the first batch of seven words that were illuminated, its size can be contained in the square light spot, and the words that are illuminated later, are either big or wide, even though there is a reason why the size of the light spot is also changing due to the angle of light, but one of the most powerful evidence can directly shatter other possibilities, that is, except for the first batch of seven words that can be connected into sentences, other words can not be read。

The seven characters are: township, no, cloud, country, other, thing, and special.

"The clouds are not different, the country is different. Yan Qi said.

"Speak human words. Yuan Chang said.

"Du Fu's poem, the title of the poem is "Xiao Zhi", "When Yan Qi dictated the poem to the three-year-old Young Master Yan Jiu, he memorized this poem with him," The last four sentences of the poem are: "The shore is waiting for the willows, and the mountains are cold and want to release plums." The clouds are not different from the country and the country, and the children are taught to cover the cup in the palm. The meaning of the phrase "Yunwu" is roughly as follows: Although I am in a foreign land, the scenery here is no different from that of my hometown. ”

Yuan Chang looked at the seven words on the pavilion pillar, then turned his head to look at Yan Qi, with a look of "You can show me this when I take off my pants": "And then?"

"What, then?"

"Just such a poem, and then what's the intent?"

Yes, it's to solve problems and run to wait for the sunset, and then come up with such a poem that is neither classic nor popular, what is the purpose of the whole set of people?

"I can't figure it out, I'm going back to training. "Yan Qidao.

The two of them simply ran back to the training ground.

Yan Qi was punished by Wu Changge for running ten laps around the Tengfei Field.

The reason is that after pulling your stomach for so long, I haven't seen your stomach deflated a little, do you say that you are embarrassed to burn fat without being punished with a shy face?

On the way home, Yan Qi asked Young Master Yan Jiu: "'The clouds and things are not different from the country and the country', what can you think of just listening to this poem?"

Young Master Yan Jiu slowly glanced at her: "Guess the riddle?"

Oh, poetic riddles, quite possibly.