r18novel Chapter 5 Written Test
Chapter 5 Written Test
The next morning at 7:20, Lin Shen arrived at the Feixun office ten minutes early.
He was like a hunter, waiting precisely for his prey.
At 7:25, Lao Wu appeared in the office. He first made himself a cup of instant coffee, then frowned at the computer screen, which was probably showing another endless list of bugs.
Lin Shen got up and knocked on the door with his knuckles, neither too hard nor too soft.
"Go in." Old Wu didn't even look up.
Lin Shen pushed open the door and stood in front of the desk piled high with documents. Old Wu then looked up at him, his brows immediately furrowing in his habitual manner: "What is it? The morning meeting is about to start."
"Manager Wu," Lin Shen's voice was unusually calm for someone his age, "I've analyzed the data from the monitoring tool we deployed yesterday, which was running smoothly under low load conditions at night."
However, I suspect it might have hidden issues under peak concurrency conditions—such as buffer contention or inappropriate lock granularity. I need to conduct on-site stress testing in the data center, ideally capturing the raw packet interaction data at the underlying layer.
Old Wu put down his coffee cup and stared at him for several seconds: "Now? The morning meeting is about to start, and there are still more than thirty bugs to be assigned today."
"The problem might only appear within a specific time window." Lin Shen's tone remained calm. "If we don't collect data now, and something goes wrong during tomorrow's morning rush hour, the whole team will have to stay up all night again. Of course, if you think waiting until a problem arises before putting out the fire is more in line with the team's rhythm, then I'll go back to the morning meeting now."
After he finished speaking, he waited quietly.
Old Wu tapped his fingers on the table, making a dull "tap, tap, tap" sound. He glanced at Lin Shen, then at the red bug list on the computer screen, and finally waved his hand impatiently: "Fine, fine, go ahead. Remember, read-only permissions, don't touch any production configuration!"
"clear."
Lin Shen walked back to his workstation, took out his backpack from the drawer, which contained his personal laptop, charger, and a bottle of water. He then picked up a piece of white paper and a pen from his workstation, slowly zipped it up, and then walked through the office area towards the stairwell amidst the sound of keyboard clicks.
The metal door to the server room clicked shut behind me.
The world suddenly sounded different.
The low, continuous hum of dozens of server fans sounded like the breathing of some giant creature, the dense indicator lights flashed on and off, and there was a faint smell of ozone and the distinctive scent of metal heat sinks in the air.
The temperature here is at least five degrees higher than outside.
But Lin Shen had no choice. He found a temporary workstation for maintenance in the corner, turned on the computer in the server room, and then turned on his own laptop.
[Current Location: Feixun Technology - Server Room]
[Environmental Factor: 0.4]
It's exactly the same as the office area.
Lin Shen looked at the number and twitched the corner of his mouth. The system was indeed ruthless—even if you stayed in the place closest to the "heart" of the company, as long as the work you were doing was essentially repetitive maintenance, the coefficient would not change.
He glanced at the time: 7:40.
There are still two hours and twenty minutes until the written exam at 10:00 AM.
Another line of the system interface displays:
[Moyu Coin Balance: 0.3]
He needs to collect 1 coin to use [Bullet Time - Beginner], which means he needs 0.7 coins and 105 effective slacking-off time.
That's enough!
Lin Shen entered a few monitoring commands into the terminal, causing the server logs and data streams to start scrolling on the screen. Then he leaned back, the swivel chair creaking as he lifted his feet and placed them directly on an unused server chassis next to him, his shoes rubbing against the cool metal surface of the chassis.
His posture was as relaxed as if he were on his own sofa.
[Valid time spent slacking off detected: 0.1 hours...]
As his slacking-off time began to accumulate, Lin Shen mentally reviewed the knowledge points he had compiled in yesterday's "Quick Archive" section.
At 9:30, Lao Wu pushed open the computer room door for the second time.
Old Wu walked in.
He first habitually looked up at the large monitoring screen on the wall—which displayed real-time curves of CPU, memory, and network traffic for each server. Only after confirming that all indicators were in the green zone did he shift his gaze to the depths of the server room.
Then he stopped in his tracks. Was this kid slacking off? No…
In the corner, at a chipped iron table, Lin Shen was slumped in a swivel chair in an extremely strange posture: his head was tilted back, his neck bent at almost a ninety-degree angle, and his Adam's apple protruded abruptly; his eyes were half-open and half-closed, his gaze unfocused as he stared at a stain on the ceiling; his lips were moving slightly, muttering something but the content was incomprehensible; his hands hung at his sides, but his fingers tapped in the air like he was playing the piano, as if there was an invisible keyboard in front of him.
What made Lao Wu even more uneasy was the expression on Lin Shen's face.
His lips were upturned, giving the appearance of a smile, but his eyes held no joy, instead appearing frighteningly empty. His entire face, under the fluorescent light, had an unhealthy pale bluish tinge, which, combined with his unfocused gaze and neurotic finger movements, made him look like... a madman trapped in his own world.
"Lin Shen?" Old Wu called out tentatively, his voice sounding somewhat weak in the empty server room.
no response.
Old Wu frowned, took a few steps closer, and raised his voice: "Lin Shen!"
Lin Shen suddenly turned his head.
His movements were as swift as a spring, and his neck cracked softly. His eyes focused instantly, pupils contracting, staring directly at Old Wu's face. His gaze was unusually bright, like two dark flames burning within, causing Old Wu to instinctively take a half-step back.
"Manager Wu," Lin Shen said, his voice a little hoarse but filled with barely suppressed excitement, "You've come at the perfect time. I've discovered something very interesting."
Old Wu felt uneasy under his gaze: "W-what is it?"
"Look at this server," Lin Shen said, pointing to a Dell rack server humming softly beside him, his finger almost touching the chassis. "I monitored its fan speed curve and TCP retransmission rate fluctuations for half an hour, and guess what?"
Old Wu stared at the dark computer case, completely clueless as to how to guess.
"There's a peculiar phase difference!" Lin Shen revealed the answer himself, his voice trembling slightly with excitement. "Every time the fan accelerates—whoosh!—three hundred milliseconds later, the network stack buffer will have a slight tendency to overflow. Look at this diagram."
He quickly typed a few keys on the keyboard, and a waveform graph with alternating red and green colors popped up on the screen.
"The peak values of these two waveforms are always 300 milliseconds apart. Perfectly synchronized, down to the second!" Lin Shen turned around, his eyes gleaming. "Manager Wu, do you think this is some kind of resonance effect? Is the mechanical vibration transmitted to the motherboard, affecting the electrical stability of the network card chip? Or... is there some anomaly in the geomagnetic field of this building?"
Old Wu stared at the fluctuating curves on the screen, completely unable to understand them. All he could see was Lin Shen's face, flushed with excitement, his unnaturally bright eyes, and the way he was waving his arms and speaking faster and faster.
"What's even more amazing," Lin Shen suddenly lowered his voice, leaning forward as if to share some earth-shattering secret, "Manager Wu, do you know what? It's just like life!"
Old Wu was completely dumbfounded: "...What's like life?"
"Packet loss!" Lin Shen spread his hands, like a fanatical believer preaching in the street. "A data packet is sent out, but no ACK is received. It may be really lost and never reach the other end; or it may just be delayed and queued in the queue of some router, and will arrive in a while—just like the effort you put in, it may not be rewarded immediately, it may just be that the time is not right yet."
He stood up and paced in the narrow aisle, his finger tracing invisible lines in the air: "But if you keep retransmitting, sending a packet, waiting two hundred milliseconds, no response, sending again, waiting again... the system will become congested, the bandwidth will be saturated, and the truly important data won't get through. Life is like that too. If you're too obsessed with something, constantly 'retransmitting,' constantly forcing it, life will fall into a vicious cycle, and other important possibilities will be blocked..."
He spoke with exaggerated gestures, his eyes darting around, and a sickly blush spreading across his face.
Old Wu stared, speechless.
He looked at the intern before him: sleeves rolled up to his shoulders, hair slightly disheveled with excitement, eyes shining as if they were about to burst into flames, and speaking in a "technical philosophy" that he couldn't understand at all. At that moment, he had only one thought in his mind:
Has this kid gone crazy from working overtime non-stop?
That's not right, he's been leaving get off work at the normal time these past two days...
"So sometimes," Lin Shen suddenly stopped, turned around, and stared directly at Lao Wu, "you have to learn to let go. Let go of what you should let go of, let go of what you should leave. The system will adjust its congestion window automatically, and life... will find its own way out. Don't you agree, Manager Wu?"
Old Wu's Adam's apple bobbed, and he said dryly, "You...you should finish your work first. Don't think about these...these mysterious things."
"Work? Yes, work." Lin Shen grinned, a smile almost too bright. "I'll definitely work 'well.' After all, work is for making a living. But Manager Wu—"
He leaned forward, lowered his voice, as if he were telling some incredible secret:
"Have you ever thought about this: if life itself becomes work, getting up is going to work, eating is refueling, and sleeping is shutting down for maintenance... then what are we living for? Just to get up and 'go to work' again tomorrow?"
Old Wu was so flustered by his question that his scalp tingled.
He felt that Lin Shen was acting strangely today, but he couldn't quite put his finger on it—he was definitely "working," the screen was displaying monitoring data, and what he was saying seemed to be related to technology, but it was his demeanor… his eyes… his smile…
It's so frightening.
"...You can continue." Old Wu finally chose to retreat. He turned around, his steps much faster than when he came, almost as if he were fleeing towards the door of the server room.
As he reached the door, he couldn't help but look back.
Lin Shen had slumped back into his swivel chair. His head was tilted back, his neck bent at an odd angle, his eyes fixed on the ceiling, and his fingers were tapping in the air. He was muttering to himself, a half-smile playing on his lips.
Like a madman immersed in his own world, completely isolated from the outside world.
Old Wu muttered to himself as he pushed open the door and left, deciding not to come to the computer room again before leaving get off work today, out of sight, out of mind.
The computer room door clicked shut.
Lin Shen's "mad" expression vanished instantly.
He sat up straight and rubbed the back of his neck—it was a bit sore from holding that position for so long. Then he glanced at the system interface:
[Valid time spent slacking off detected: 0.8 hours]
[Slacking off coins +0.32]
[Cumulative "Slacking Off" Coins: 1.02]
My casual conversation with Lao Wu just now also counted as slacking off, perfect!
If he wasn't afraid that Lao Wu would come in during his written exam, he really wouldn't have put on this show; it's crazy enough!
At 9:55, the laptop connected to the mobile network.
At 9:58, I opened my browser and entered the URL of Tencent's written test system.
At 9:59, he logged in—he had already memorized the account and password.
At 10:00 AM sharp, the written test page refreshed on time.
Part 1, Computer Basics, 30 multiple-choice questions.
Lin Shen glanced at the questions and twitched his lips. Most of them were things to memorize: the function of each layer of the OSI seven-layer model, the difference between processes and threads, the four necessary conditions for deadlock... To him, these knowledge points were as natural as breathing.
Twenty-two minutes later, the first part was completed.
The system automatically jumps to Part Two: Logical Reasoning, 20 questions.
Graphical reasoning, numerical sequences, linguistic logic… Lin Shen got stuck on the third question—a complex cube unfolding and rotation problem. He stared at the screen for half a minute, then clicked "Mark, answer later".
jump over.
He worked with ease, even a little...enjoying it. With each problem he solved, he told himself: "See, this is life without overtime, without fixing the 'move the button 2 pixels to the left' bug, without listening to Lao Wu yelling. Pure logic, clean thinking, how wonderful."
At 45 minutes, the first two parts were completed.
The system then redirects to the programming challenge section.
First question: Given a string, find the longest palindromic substring.
A classic problem. Lin Shen barely needed to think; his fingers flew across the keyboard. He wrote a center expansion algorithm with a time complexity of O(n²) and a space complexity of O(1). After finishing, he thought for a moment and added a comment:
"If the string length exceeds 10^6, it is recommended to use the Manacher algorithm, which can reduce the time complexity to O(n). However, considering that the problem explicitly states that the input size is relatively small, and that the Manacher algorithm is relatively complex to implement and has poor readability, the center expansion method, which is easier to understand and maintain, is adopted."
This demonstrates both breadth of knowledge and the trade-offs in engineering.
The second challenge is a variation of the sum of two numbers problem: find all unique pairs of elements in an array that sum to the target value.
It was another problem type we'd focused on reviewing last night. Lin Shen first sorted the array, then used two pointers, carefully handling duplicate elements. After finishing the code, he specifically tested several boundary cases: an empty array, all identical elements, and the target value being smaller than all elements…
At 11:05, two programming questions were submitted.
The system is redirecting for the last time.
The last question: System design.
The problem description is shockingly concise: "Design a simple instant messaging system that supports one-to-one text message sending. Briefly explain your design ideas from the perspectives of client, server, protocol, and storage, and focus on how to ensure reliable message delivery."
Lin Shen stared at the line of text and remained silent for a long time.
The humming sound from the server room continued in my ears.
He had the answer. He had it all too well—in his previous life, he spent seven years on the WeChat team, participating in the entire evolution of the messaging system from simple to complex, from single-machine to distributed. He knew where every pitfall lay, the cost behind every trade-off, and the pain of every architectural upgrade.
But he cannot write.
现在是2010年。iPhone 4刚刚发布，Android 2.2还叫Froyo，行动网路主要是2G和初生的3G，智慧型手机普及率还很低。他不能把2018年的微信架构直接搬过来。
He needs to write a solution that "a smart person in 2010 would come up with".
A solution that was in line with the technological realities of the time, yet subtly revealed a hint of foresight.
A solution that is both solid and a little "clever".
Lin Shen began typing.
He wrote quickly, but with great restraint:
Client-side: Based on TCP long connection, with heartbeat keep-alive (once every 30 seconds) and automatic reconnection after disconnection (exponential backoff).
Server: Simple connection management (using a dictionary to store userId->socket mapping), message routing (lookup dictionary for forwarding), messages are first stored in an in-memory queue and then asynchronously flushed to disk files.
Protocol: Custom binary protocol, with the header containing message type, length, sequence number, sender, receiver, and timestamp.
Reliable delivery: The sender waits for the server's ACK, and the server sends back an ACK after successful storage. The receiver sends back a delivery receipt upon receiving the data. Each step has a timeout retransmission limit of up to three times.
He stopped writing here.
He looked at what he had written on the screen, and his brows slowly furrowed.
Too ordinary.
This is like a textbook-style standard answer, something any college student who has studied web programming could write. It's flawless, but it's also utterly unremarkable.
He needs something... different.
Lin Shen glanced at the time: 11:20. Forty minutes left.
He glanced at the system interface:
[Moyu Coin Balance: 1.02]
[Available Skill: Bullet Time - Beginner (1 coin/use)]
use.
[Use Bullet Time (Beginner)? Costs 1 Lazy Coin, lasts 5 minutes.]
【Yes】
In an instant, the world changed.
It's not that time stopped, but rather... the speed of thought was forcibly elevated to a higher dimension.
The hum of the server clusters in my ears suddenly receded, becoming blurry and slow, as if seen through a thick layer of water. The text on the screen in front of me, however, was exceptionally clear, each pixel so sharp it was blinding, and the cursor blinked as slowly as breathing, once per second.
But his mind was racing.
Those fragmented memories from the past—arguments at technical meetings, version changes in architecture documents, and post-incident reports—are no longer scattered images, but are connected and woven together by some invisible force to form a three-dimensional knowledge network.
He thought of several key points:
Mobile characteristics. It's 2010, and smartphones are on the rise. Designs can't just consider stable Wi-Fi environments; they also need to account for the instability, high latency, and frequent switching of cellular networks. A "network type flag" (Wi-Fi/3G/2G) can be added to the protocol header. The client can use this flag to determine certain behaviors—for example, not sending large image previews under 2G; and proactively informing the server to "enter power-saving mode" when the battery is below 20%, causing the server to delay the push of non-urgent messages.
Simplifying status synchronization. Early IM systems, like Mobile QQ, favored complex user statuses: online, away, busy, invisible, QQ Me... most of which were useless. A much simpler approach would have been to differentiate between only two statuses—"deliverable" and "undeliverable." Online or away but still able to receive messages? Both are "deliverable." Offline or invisible? Both are "undeliverable." Cleaner, more resource-efficient, and reduces synchronization overhead.
The evolution path of storage. Don't start by designing a complex storage architecture capable of supporting hundreds of millions of users. That looks unprofessional, and the interviewer will think you're unreliable. Instead, write an "evolutionary design": initially, with few users, use file storage + memory caching; with hundreds of thousands of users, migrate to a single MySQL table; with millions, use MySQL sharding; with tens of millions, introduce NoSQL for hot and cold data separation, storing hot data in Redis and cold data in HBase. This is called pragmatic foresight—I know what the future holds, but I start with the simplest and most reliable approach.
A small innovation: A "content feature tag" can be added to the message header—for example, whether the message is plain text, an image, voice, or a file. The client decides whether to preload non-text content based on the current network conditions and battery level. For example, under Wi-Fi, a small image preview is automatically preloaded; under 3G, only text is loaded, and images are only downloaded when the user clicks on them. This was still a very new concept in 2010.
Thoughts flowed out like a burst dam.
Lin Shen's fingers flew across the keyboard. He wasn't writing code, but rather outlining his design concepts. He abandoned lengthy paragraphs and adopted a clear, itemized structure.
He wrote so fast that his fingers almost left afterimages on the keyboard.
Five minutes, three hundred seconds.
At a mental acceleration of 150%, this is equivalent to seven and a half minutes of high-quality output time.
When the notification that the [Bullet Time] effect had ended appeared, Lin Shen had already filled two entire screens of the answer area.
He stopped writing and quickly scrolled through what he had written.
The logic is clear and the structure is well-organized. The foundation is solid and impeccable, while the innovations are just right—neither too far ahead of their time to be detached from the technological realities of 2010, nor too far ahead of their time to subtly point to the future development direction of mobile internet.
perfect.
He let out a long breath, feeling a throbbing sensation in his temples. The aftereffects of his intense, accelerated thinking were beginning to appear; he felt a little dizzy and nauseous.
But he had no time to rest.
It's 11:25, with 35 minutes left.
He went back to the beginning of the exam paper and started checking each question one by one, beginning with the first multiple-choice question. He corrected two careless mistakes in the answer choices and optimized the boundary condition comments for a programming question.
At 11:55, there were five minutes left until the deadline.
He scrolled through the page one last time to make sure nothing was missed.
Then, move the cursor to the "Submit" button at the bottom of the page.
Click.
The page redirects, and a line of simple blue text appears:
"The written test is complete. Thank you for participating. The results will be sent to you via email within 3-5 business days."
Lin Shen leaned back in his chair and closed his eyes.
[Moyu Coin Balance: 0.76]
ha?
Does taking exams count as slacking off?
Lin Shen experienced almost double the happiness at this moment.
However, the aftereffects of "bullet time" are still there, but the feeling of clear thinking, bursts of inspiration, and the ability to see the flow of knowledge in front of you during bullet time is truly addictive.
He sat in the chair for a long time, until his heartbeat gradually calmed down and the dizziness subsided, before he began to slowly and methodically pack his things.
"Manager Wu, the toolkit is deployed!"