Chapter 16 Greetings from Mitarai: Digital Lock Chapter 3

【Greetings from Mitarai: Digital Lock】 "How many exits are there?" "Two. I prepared a schematic diagram: one exit is this rolling door, and the entire facade facing the road is a rolling door. This door is locked from the inside. Put down the rolling door and push the bottom pin of the rolling door to the left and right. It can be locked in the chute on both sides." "So, can the rolling door only be opened from the inside? In other words, it cannot be unlocked without entering the room?" "No, that's not the case. Of course, the lock can be easily unlocked and locked from the inside as I just said, but it can also be done from the outside with a key. There is a key hole on the outside of the rolling door, and the key is given by the middle-aged staff of the truck to work. The oldest Tatsuo Akita took care of it. On the morning of the twelfth, it was this Tatsuo Akita who opened the rolling door with the key and found the deceased. The key was only held by the employee Akita. There were two keys in total, and the other was in the hands of the president. Not even Kitagawa Yukio."

"I see. Then, the one with the combination lock is the side exit, right?" "Yes. It says 'Inner Wooden Door'. It's true. There's only one wooden door that allows access to the side passage. That kind of digital lock is installed under this door, facing the road outside. Actually The lock can be knocked open with something, and the door panel is not very strong, and it is not impossible to kick it open, but there is no such trace at all-there is no sign of forcibly broken." "So, no matter how much it looks like a toy, the door can't be opened if the three passwords don't match, right?"

"Yes. There is no trace of opening here, but..." "Who knows the password?" "neither knows." "neither knows?!" "Yes. The only one who knows the password is the president. President Suita bought this lock and set the password himself. It seems that the president said that if he told the staff, it would definitely be leaked to outsiders, as long as he knew it alone. I didn’t even tell my wife. But that’s all, no one will use this wooden door at all. Just opening and closing the rolling door outside is enough for daily use.” "I see. Even the staff don't know the password of the digital lock. Of course, Ishihara and Bachang are even less likely, right?"

"That's why we're so confused." "That's right." Mitarai said happily, clasping his hands together gratefully, "Then the only remaining entrance is the rolling door?" "Supposedly, this is true, but it is impossible to realize. Anyway, Ishihara and the horse farm do not have the key to the rolling door after all." "When they were in a relationship with Suita before, wouldn't they steal the key and secretly match one? Or maybe they had relationships with the five members, such as drinking together or something, if they steal the opportunity, they can get it done in thirty minutes gone."

"Ishihara, Baba and Suita Denshi's staff have never met each other, and it is impossible to communicate with each other." "As for the president, he has been very vigilant since that incident, and has no contact with those two people at all. Besides, Suita didn't trust those two people very much before. Can we really find that kind of opportunity?" "But if you can't pass through the wooden door with a digital lock, then only the rolling door is left?" "That's true. But the rolling door will make a loud noise. There is a couple living on the second floor of the building rented by Suita Denko. The couple testified that the rolling door closed at around 6:30 in the evening on the eleventh, and on the twelfth The rolling door opened before ten o’clock in the morning—this was the sound of the four of Ogiki’s door opening when they went to work—there was no sound of the rolling door opening and closing at all during this time. This kind of rolling door makes a loud noise, and the people who live on the second floor It's easy for people to notice."

"What if we spend a little more time and slowly open the rolling door bit by bit? Then the residents on the second floor won't notice, and won't wake up President Suita who is sleeping on the sofa." "Between eight and nine in the morning? There were already a lot of people on the road at that time, and I don't know when the staff will go to work." "There are two keys to the roller door, right? Where's the other one?" "In the pocket of the president who was killed, in the right pocket of his trousers." "Ha, so to speak, stole the key in advance and slowly opened the rolling door in the middle of the night, pretended to chat with Suita, assassinated him after he fell asleep, then slowly lowered the rolling door, locked it and put the key back in Suita Shrine In the long pocket—Isn’t that impossible, Ishioka-kun?”

"Isn't this nonsense!" "Anyway, the time to close the rolling door is from 8:00 am to 9:00 am, right? Officer Takegoshi, are there many people on the road at this time?" "Quite a lot, there are a lot of staff coming and going at work." "Aren't there any witnesses?" "not yet." "If I would definitely avoid going in and out through the rolling door to the outside. With that purpose in mind, I should find a way to go through the wooden door inside anyway. It's at the end of the alley, right?" "Yes. And at that time, there were many cardboard boxes of materials piled up at the door. If you squat down, you won't be seen by passers-by."

"And if you squat down to try the digital lock, no one will see it, right... Are there any fingerprints here?" "Only Mr. Suita's. Even if the murderer invades from here, he will wear gloves—the same goes for knives." "Oh..." Mitarai thought, "In addition, the racecourse and Shiyuan, no matter whether they entered through the rolling door or the wooden door, what is the possibility of committing a crime? Did they have any evidence of abnormality during the death period?" "It's also possible in terms of time. Let me give you some details about the two of them: first, Bachang Kazuo, thirty-nine years old. He works honestly in a trading company. It is said that on December 12, he and He usually left Yotsuya's apartment at 8:20 in the morning. His wife testified about this, and he also met the administrator when he left the apartment, and there was also testimony.

"It takes about ten minutes to walk from the apartment at the racecourse to the Yotsuya Station, and you won't pass the scene on the way, because the apartment and the scene are sandwiched between the Yotsuya Station, in two directions. He arrived at the Yaesu company before 9:50 and called Time card. The card clearly shows that it is 8:55, and the time to enter the company is not only the time card, but also the colleagues of the racecourse company can prove it, so it is impossible for him to arrive at the company before 9:5 There is something wrong." "In this case, according to common sense, on December 12th, the horse farm Kazuo only has time to go to work on the tram in the morning. Of course, the possibility of him driving quickly to Suita Denshi for a lap cannot be ruled out. However, the horse farm does not have a driver's license."

"On the other hand, Ishihara Shuzo, who is not so honest at work, his alibi is also very vague, almost nothing. Originally, it was difficult to provide an alibi at the time of 8:00 am to 9:00 am. The honest and hardworking people are at work On the way. As for Playboy, he is still asleep at this time—Ishihara Shuzo is no exception, we checked, and he is indeed sleeping on the bed." Officer Takegoshi explained while looking at the notes, and subconsciously changed to the tone of the search meeting, as if this way of speaking had already been imprinted on him, "The so-called sleeping on the bed is not in his own home, but in the lover's house in Qiandaigu. The situation is more troublesome. It is said that he didn't get up until twelve o'clock at noon. The woman who has been sleeping next to him can testify that, However, the credibility of the testimony is still questionable. Ishihara has a driver's license and also has a car. But his car has been parked in the monthly subscription parking lot on Nakanosaka on the 11th and 12th. This starts with his wife, parking People around the scene testified. Therefore, it is certain that his car did not move at the time of the crime, but the distance between Sendaiya and Yotsuya is only two stops by tram.”

"That's right. What did they themselves say about the case?" "They all say that they have nothing to do with them. Although they hate Suita, killing him is absolutely nonsense." "I see. Then, please tell me the situation of the staff in detail." "You mean Yukio Kitagawa? This man is thirty-four years old, and he has good skills. He can be the arm of President Suita. He only has a wife, and he rents an apartment in Yotsuya about 15 minutes' walk from the company. Then he lives in Ogaki A group of four who drive a truck to work. The oldest is Akita Tatsuo, the one who keeps the keys to the rolling door, aged 26. There is Oku Koichi, aged 24; Tomono Juntaro, aged 21; Miyata Cheng, seventeen years old. Except for the youngest Miyata, everyone else has a driver's license. But except for Beichuan, no one else can draw their own signs. Their work is mainly carrying signs, and loading and unloading up and down. .This is also a job that requires proficiency.” "Where is the dormitory?" "Is their residence? No. 2-41-X, Amenuma, Suginami-ku." "Where's Suita Denko?" "No. 1-6-X, Yotsuya, Shinjuku-ku." (According to the stop sign of the JR Chuo Rapid Line, there are four stops between Ogaki Station and Yotsuya Station, and it takes about 15 minutes by tram one way.) "Oh, that's it." Mitarai didn't seem to intend to remember at all, as if asking was useless. "Well, the above case has been introduced. If you have any ideas, teacher, please let me know." "Aside from Ishihara and Bachang, are there any other suspects?" "I can't see it at all." "You can't be so sure." "Did you say it can't be limited to these two people?" "Isn't it completely impossible? For example, can you completely deny the possibility of simple theft? The thief sneaked in to steal something, but unexpectedly found the president sleeping inside, afraid that he would kill him if he got up and found out?" "It shouldn't be possible. First of all, President Suita's coat was on the workbench near him. He was sleeping under a blanket, and there was a wallet in the inner pocket of the coat with 470,000 yuan in cash. This is The cash has not been touched at all." "Oh, there's another thing!" In this way, Mitarai was even happier, and put his palms together.I saw him ready to move at this moment, "Since it's a company, naturally there is a phone in the room?" "certainly." "Then the horse farm and Ishihara and Suita are a speculative combination, so they are naturally familiar with each other?" "That's right." "Then there is no way to make this impossible case possible." "What do you mean by that?" "If these two are accomplices, anything is fine. Either one, call Suita outside, drink with Suita while Hotel Eleven is still open, get him drunk, steal The key to the rolling door. Then give the key to another person who is waiting, and this person will open the rolling door, and then return the key to the hotel companion, who will secretly put the key back on Suita. Then the prisoner returns to the open door. The Suita Denko of the door, enter the room, hide in a shelf or something and wait for Suita, the rolling door can be locked from the inside anyway.” "But is this really possible?" Officer Takegoshi retorted immediately. "Testimony from residents on the second floor? But isn't that referring to the situation where the rolling door is swung open to the ceiling? The sound is indeed loud, but if there is only a gap where a person can bend down and get in, it is not necessary. It's very high, the sound won't be very loud if you turn it on slowly, right?" "But according to the method you said, the key to the rolling door is still inside. Whether Ishihara or Baba stays at the scene, even if you can easily kill Suita, you still can't lock it when you go outside after the matter is over. Roll the door!" "Then how about getting another key when you steal it from Suita?" Officer Takegoshi shook his head, as if he had had enough: "How could a locksmith be open at that time?" "Besides, just now he used tricks to buy and sell stocks, how could President Suita be called out by those two people so easily?" I kept watching from the side, and couldn't help but say at this time. "Besides, teacher, Ishihara Xiuzao No. 11 has a reliable alibi until late at night. He runs his own restaurant until about three o'clock in the evening. The staff and many customers in the store can confirm. The racecourse also drinks in Ginza until late at night. At eleven o'clock, there are people in the store who can prove it. Then his family members testified that he returned home just after twelve o'clock." "Really, what a pity! Then this line will be useless." Mitarai said while standing up energetically.But I can see that behind this sentence, he is actually very happy, and he estimates his true meaning in his heart. "Teacher, I want to ask, how many combinations of digital locks are there?" Officer Takegoshi asked Mitarai who was pacing back and forth in the room. I don't know if he heard it, but Mitarai thought about it and didn't speak.He stared at the floor, walked around the room with his hands behind his back, occasionally stopping to mutter something. "Hey, Mitarai-kun!" I couldn't help but say.But he didn't always act quickly, as if his mind was occupied by something and completely fascinated. No way, we have been waiting.He kicked the packed things, and finally answered: "Ishioka-kun." Mitarai said, "Have you packed the things in your own room?" "It's not packed yet," I replied.We originally planned to pack up our things separately, leave this house, and move together to a bigger house in Yokohama Bashamichi. "Now go to your apartment and get your stuff together." "Mitarai-kun, can't this matter be done later!" "No, go now, it's best." "Hey, Mitarai-kun, wait a minute!" I hurriedly reminded Mitarai, "What about the digital lock? How many combinations are there?" "What?" Mitarai stopped packing her things and asked back. "A combination lock? Ah, that! A combination lock. Does that combination number go from one to nine or include zero?" "Includes zero, too." "Then it's ten numbers. Ishioka-kun, do you know how many possible batting orders there are for nine people?" "I do not know." "It is the factorial of nine, 9×8×7×6×5×4×3×2×1, 362880 kinds. Right now, this equals a baseball team of ten people, which is 10×9×8×7×6×5× 4×3×2×1, a total of 3,628,800 combinations.” "Are there so many combinations of digital locks?" "Yes. Starting from 111, 112, 113, if you try one by one, assuming that it takes two seconds to try each one, it will take 7,257,600 seconds to try all of them." "How many hours is this?" "7257600 seconds divided by 60 is 120960 minutes, and then divided by 60 is 2016, that is, 2016 hours, divided by 24 hours in a day is equal to 84, that is to say, it will take 84 days to try it all. More than a month and a half." What an astonishing calculation, Mitarai just calculated it out of thin air. "Eighty-four days, that's impossible." I heard Police Officer Takekoshi muttering. (I also know that this calculation is completely nonsense. There are only 1,000 combinations of ten numbers and three digits. The original work is written like this here... I was shocked when I saw this, and quickly checked the evaluation. See, but based on the comments it seems like the author is trying to keep it secret. So don't throw eggs at me.)