After putting away the juice drinks, Jing Sicun stood up as if nothing had happened, balled up the tissue he’d used to wipe his face, and tossed it into the trash can.
Then he sat on the sofa less than half a meter away from Ke Ni.
With Jing Sicun’s parents present, Ke Ni couldn’t let her temper show.
She picked up the bottle of juice, twisted the cap, and used drinking it as an excuse to keep her mouth shut.
Jing Sicun glanced at Ke Ni with a smile, picked up the cola from the coffee table, and twisted it open.
He took two sips of cola.
“There’s something off about the number of colas in the fridge. Dad, did you sneak a drink again?”
Jing Sicun’s mother shook her head.
“Your father’s been behaving lately. The neighbor’s kids came over with their parents yesterday, so I gave the colas to the children.”
Ke Ni knew nothing about Jing Sicun’s family circumstances.
Her thoughts began to wander uncontrollably:
Why can’t Jing Sicun’s father drink carbonated beverages?
Is it to control his blood sugar?
Or does he have a sensitive stomach?
Suddenly, the ill-tempered old man lying in the bedroom started shouting, “Talking behind my back! Someone’s talking behind my back!”
Ke Ni jumped in fright.
Did the old man mishear something?
Jing Sicun stood up.
“I’ll go say hi to Grandma before we leave.”
Jing Sicun’s mother said, “Sicun, it’s time. Remind Grandma to take her medicine too.”
Ke Ni stayed in the living room and heard Jing Sicun’s grandmother say, “Who are you?”
Jing Sicun replied, “Einstein.”
“Who are you?”
“The Jade Emperor.”
“Bad boy! Talking behind my back!”
Ke Ni seemed to recall reading somewhere that at a certain stage of Alzheimer’s, paranoia could occur.
Maybe Jing Sicun’s grandmother was at that stage of the illness now?
Jing Sicun didn’t mind being scolded, and patiently coaxed her, “This energetic old lady, as lively as a Tuesday, don’t fuss. Take your medicine first.”
“Bad boy!”
Jing Sicun’s mother smiled at Ke Ni, a hint of apology and helplessness in her expression.
Not wanting the elders to feel awkward, Ke Ni switched the topic to cover up her distraction, “Auntie, have you ever met He Zhi and Dai Fanze?”
Jing Sicun’s mother said she had, and also mentioned hearing that He Zhi was nervous lately because of competition preparations.
Then she asked Ke Ni how her own preparations were going.
Ke Ni admitted, “I’m even more nervous than He Zhi. After all, I’m not as impressive as them.”
Ke Ni’s mother said, “Don’t say that. Any kid who made it through the preliminary rounds is already outstanding.”
Ke Ni said, “Auntie, I’m not like Jing Sicun and the others. I’ve never had any dazzling achievements since I was little…”
She always felt that making it through two rounds of preliminaries might have just been because she happened to have practiced similar skills before.
Jing Sicun’s father couldn’t control his facial muscles, so his cheeks twitched every time he spoke.
It looked a bit frightening, but the things this elder said were especially considerate.
Jing Sicun’s father said, “Xiao Ke, life is about luck. Look at the roses outside.”
Ke Ni followed Jing Sicun’s father’s gaze to see several pots of roses blooming on the open-air balcony.
Jing Sicun’s father said, the earliest batch of roses should have monopolized the beauty of spring, but they encountered a frost and withered before they could bloom.
Instead, the buds that grew later, after absorbing enough nutrients during dormancy,
blossomed brilliantly after accumulating strength.
Jing Sicun’s mother nodded.
“Not having good results before doesn’t mean you won’t in the future.”
Ke Ni was momentarily stunned.
The shouts of “bad boy” from the bedroom gradually faded.
Jing Sicun came out and joked with his parents, “You’re already giving people life advice the first time you meet?”
Jing Sicun’s father’s half-face twitched as he grinned.
“Sorry, Xiao Ke, I do have a bad habit of acting like a teacher.”
Ke Ni shook her head.
“Not at all, I really benefited from it. Thank you, Uncle, thank you, Auntie.”
Jing Sicun’s parents were both very kind.
Jing Sicun’s mother said that she and Auntie had made lots of canned pears and yellow peaches, packed them in clear glass jars, and wanted Jing Sicun to take some to the grocery store to give to the neighbors.
She also gave Ke Ni two jars.
Even though Jing Sicun’s father had difficulty walking, he insisted on seeing them off to the elevator.
Jing Sicun’s mother reminded Ke Ni, “There are no additives in the canned fruit, so keep it in the fridge. Ke Ni, you’re welcome to come by and visit anytime.”
Ke Ni was good at acting obedient in front of elders.
She knew she would probably never come again, but she still nodded and thanked them once more.
As the elevator doors slowly closed, Ke Ni suddenly jabbed Jing Sicun’s side with the juice bottle in her hand.
Jing Sicun laughed.
“Why do you have two faces?”
Ke Ni kept a straight face and ignored him.
Jing Sicun needed to head back to the grocery store, and if Ke Ni was going back to her rental place to rest, it was on the way.
But she’d delayed too long, so now she had to go straight to Professor Wang’s house for class.
Ke Ni took out her phone and opened the ride-hailing app.
“Let’s go our separate ways.”
Jing Sicun directly opened the passenger seat door.
“Where are you headed? I’ll drive you.”
Ke Ni hesitated.
Jing Sicun said, “You came to help me, I can’t just let you go back alone. Get in.”
In the end, Ke Ni got into Jing Sicun’s SUV, a vague feeling lingering in her heart, like mist she couldn’t grasp.
Jing Sicun clearly knew how to take care of the elderly, and even if he didn’t, his mother was at home.
So why did he bring her back with him…
Ke Ni pondered this question all the way to the gate of Professor Wang’s community, but couldn’t come up with a reasonable explanation.
Professor Wang’s house was quite far from the grocery store.
Before getting out of the car, Ke Ni originally planned to say thank you.
Jing Sicun spoke first.
“You’re welcome.”
Ke Ni sucked in a breath.
“Did I say thank you yet?”
Jing Sicun grinned.
“I predicted you would.”
Annoyed, Ke Ni slammed the car door shut.
Jing Sicun rolled down the window.
“Ke Ni.”
“What!”
“Thank you.”
Ke Ni pointed at Jing Sicun angrily.
“You’re not getting any more dumplings from me! We’re even now.”
With that, Ke Ni strode off without looking back, leaving Jing Sicun laughing behind her.
What Ke Ni never expected was—
She was already sitting in Professor Wang’s house, yet she would hear the name “Jing Sicun” again—
Professor Wang played a video clip from a foreign brainpower competition.
After the rules of the question were explained, Professor Wang paused the video and asked the three of them,
“What are the key points of this question’s rules?”
The rules in the video were long and elaborate, taking nearly two minutes to describe.
Seven hundred and forty 3D shapes rotated on the screen, accompanied by tense sound effects.
Over eight thousand edges.
Tens of thousands of possible paths.
A twelve-minute countdown, during which contestants had to mark as many correct starting and ending points as possible.
The contestant with the most wins…
It was dizzying.
Even just understanding it was hard.
Ke Ni quickly filtered out the distracting and misleading information in her mind and found the useful conditions:
In short—the rules required contestants to find, among the irregular 3D shapes, those that could be traversed along every edge exactly once without repeating any path.
After finding them, mark the starting and ending points.
Lin Xirun obediently raised his right hand.
“Professor Wang, is this a basic graph theory question?”
Feng Zi’an looked at the computer screen through his nostrils.
“The Seven Bridges of Königsberg problem.”
Ke Ni answered almost at the same time as Feng Zi’an, “Eulerian path.”
Professor Wang nodded.
“That’s right. As long as you think of the Eulerian path, you can solve this question.”
Just like Jing Sicun’s mother said, making it through the preliminary competition is already impressive.
Given enough time to think, everyone could figure out that this was an Eulerian path problem.
Once you thought of Eulerian path, calculating the degree of the vertices and finding the 3D shapes that fit the requirements wasn’t hard.
Over eighty percent of contestants would know:
Only shapes with zero or two odd-degree vertices can have an Eulerian path, and the start and end points are the two odd-degree vertices.
It’s just a matter of who thinks of it first, or who applies it first.
Professor Wang’s eyes showed approval.
“I once saw a domestic TV show where a contestant reacted very quickly to this type of question.”
Lin Xirun asked, “Who? I want to catch up on the episodes.”
Professor Wang said, “That contestant’s name was…”
Ke Ni was staring at the irregular 3D shapes, counting the degrees of the vertices, when she suddenly heard Professor Wang say, “Oh,”
Ke Ni’s pen fell.
“Jing Sicun!”
Lin Xirun jumped up.
“Wow, Jing Sicun! Professor, Jing Sicun isn’t a kid anymore, he’s about our age, and he’s competing with us this time too!”
Lin Xirun chatted excitedly with Professor Wang about Jing Sicun, and Ke Ni heard a snort from Feng Zi’an.
Ke Ni wanted to make Feng Zi’an cough up the canned fruit for her.
By the time she got back to her rental after class, it was already evening.
Professor Wang had left them some transformed versions of this type of problem, so Ke Ni was still working on them after she got home.
Lin Xirun messaged her from time to time to check answers or discuss progress, and even sent her clips of Jing Sicun solving these types of questions.
Ke Ni didn’t open them.
She remembered that competition clearly; there was no need to watch it again.
In fact, the first time Ke Ni ever heard the term “Eulerian path” was in Jing Sicun’s post-game interview.
As night fell, Ke Ni’s mother sent her a new jewelry design she’d just finished.
Her phone kept pinging, interrupting Ke Ni’s calculations.
The picture was a necklace design.
Tiny diamonds cut into various shapes outlined a complex halo setting, like a sunburst, making the main stone even more dazzling.
On the design, the gemstones used were labeled in English.
Next to the main stone, a small arrow pointed to “Paraiba.”
Below that: Neon blue.
Ke Ni replied to her mother:
“Mom, you’re amazing! When Ni Ni makes money, she’ll have you design jewelry for her!”
“Yay yay!”
At the end, Ke Ni sent an emoji she drew herself of a little girl jumping.
Ke Ni opened the design again to look at the main stone.
Neon blue.
Ni Hong Blue.
The loose stone lay quietly on soft dark gray fabric, dazzlingly bright.
When Ke Ni went abroad to see her mother, she’d seen this neon blue Paraiba gemstone in her mother’s studio.
The visual effect was stunning—Ke Ni stared at the neon blue gem for a long time.
Back then, Ke Ni imagined herself as one of the other gems placed next to the neon blue Paraiba.
White jade, amber, aquamarine, Australian opal, emerald…
All those jewels paled in comparison to the top-grade neon blue’s fluorescence.
Just like when Jing Sicun won the championship on TV, and Ke Ni sat in front of the screen, carefully hiding the fact that she hadn’t understood the “Pirates and Gold Coins” question.
Ke Ni didn’t like things or people that were too ostentatious, and she frowned at that Paraiba.
But now, she couldn’t help but walk to the window and look down at the narrow alley below…
There was no one in the grocery store.
An old man carrying a bag of apples or tomatoes walked into the store, skillfully put the plastic bag into an empty spot in the safe, and then took two jars of canned fruit.
Ke Ni recognized that canned fruit; she’d shared it with Lin Xirun and the others at Professor Wang’s house.
It tasted amazing—even someone as strict about dieting as Lin Xirun couldn’t resist.
But Ke Ni had never mentioned that the canned fruit was made by Jing Sicun’s mother.
Jing Sicun’s parents were really wonderful…
Before she got sick, Jing Sicun’s grandmother must have been a kind and gentle old lady too.
Otherwise, they wouldn’t have opened such a warm-hearted grocery store.
Ke Ni thought of the tired look in Jing Sicun’s mother’s eyes, the old lady who’d become a mischievous child, and Jing Sicun’s father who struggled to walk.
The grocery store glowed with a dim, warm light.
Ke Ni looked over.
A few days ago, she’d sat on a chair at the store’s entrance, using her tipsy courage to criticize Jing Sicun—
“So just because you went to a prestigious foreign school, you think you can look down on people?”
“Just because everything goes smoothly for you, you think you can look down on people?”
Even today, she’d said—
“I just can’t stand you gifted, smart types…”
“It’s like everything is so easy for you all.”
Oh my god, what was I saying!
Ke Ni hugged her head in guilt, not knowing how many times she’d wanted to disappear from embarrassment.
Out of the corner of her eye, she saw a tall, slender figure walking toward the grocery store under the soft glow of the streetlights.
It was Jing Sicun.
Ke Ni’s gaze was drawn to him, and she slowly lowered her hands from her head.
Jing Sicun was walking a big, bobble-headed dog, which looked a lot like a border collie.
That dog seemed very clingy.
It ran a few steps ahead, then wagged its tail and ran back to nuzzle Jing Sicun’s leg.
That must be Tuesday, right?
Why hadn’t she seen it this afternoon?
Tuesday seemed to be friends with the stray cats at the grocery store entrance; they weren’t afraid of it, still lounging lazily on the ground.
Tuesday went around sniffing their paws and bellies, then turned to Jing Sicun, bouncing and jumping, and when Jing Sicun bent down, tried to leap up and lick his chin.
Jing Sicun smiled helplessly, using his hand to gently hold Tuesday’s snout.
The scene was truly heartwarming.
Ke Ni didn’t look away.
Jing Sicun went into the grocery store, squatted on the steps, and opened canned food for both the dog and the cats.
The cats and dog buried their heads, eating eagerly, while Jing Sicun stood quietly with his hands in his pockets, watching them.
Jing Sicun’s shadow fell across the steps, stretching along them in an uneven shape.
Ke Ni watched Jing Sicun.
So the champion envied by others on TV, the one who turned things around against all odds, also had a tangle of shadows at his feet, always following him.
At that moment, Jing Sicun suddenly turned with his hands in his pockets, looking unhurriedly in Ke Ni’s direction.
Ke Ni’s heart skipped a beat.
What… was Jing Sicun looking at?
What was there to see in these old, pitch-black apartment buildings?
Wait.
Could he have seen her?
Can people downstairs see those upstairs?
Ke Ni and Jing Sicun “locked eyes” for dozens of seconds, then she panicked, squatting down to hide under the windowsill.