Sunny and the Algorithms of Gloom: Chapter 3.2

Robert hummed. "Alright. Perhaps some hands-on practice would help." He reached to the side of the table and pulled out a bag of colorful strips. Judging by the way they stuck to his arm slab, they must have been magnetic.

Robert detached the magnetic strips from his arm slabs and placed them in front of Sunny. "Here. Try sorting these by height."

Sunny looked at the strips for a moment. Each of them had a number written on the bottom and a cute animal at the top, with a green one being a frog and a blue one being a penguin. She started to smile, but then stopped.

Wasn't this all… a little too childish? First there was Elsie saying that apparently everyone except Sunny knew about objects and classes, and then the video with its smiley face, and the cartoon animals on the strips… Normally, Sunny was a fan of smiley faces, but it hadn't reassured her in this case. She couldn't help but feel like she was one step behind everyone else– even the elementary schoolers in Javaland.

She shook her head and opened the bag of magnetic strips. It didn't matter. All she had to focus on right now was understanding this. She'd catch up, right? Besides, she'd already solved the error problem… That was more than an elementary schooler could do.

Soon enough, Sunny had the strips sorted in order of increasing height. Seven cartoon animals smiled encouragingly at her. Their numbers were:

0 2 3 5 7 9 10

"Now, make a table with three columns," Robert instructed, gesturing towards the paper. "This is where you'll keep track of left, right, and mid. Start with left being 0, right being 7, and mid being 0."

Sunny obeyed. Then she took a closer look and frowned. "Why is right 7? Isn't the last index 6? Wouldn't that be a… what was it… IndexOutOfBounds error?"

"Ah, excellent question." Robert hovered higher. "That's on purpose. The thing is, we'll never be attempting to access the element at index right. It'll just represent the upper bound. We're saying that we know the value we're searching for will never be at index right."

Sunny wrinkled her forehead. "Okayy…"

"Hopefully it'll make sense later. So, say we're looking for the value 2. Let's run through the first iteration of the while loop. Left is less than right, so we update mid. Don't forget integer division."

At least Sunny was confident in her addition and division skills. She wrote down "(0 + 7) / 2 = 3."

"What's the element at index 3?"

Sunny pointed to a white chicken in the middle of the row of strips. It had the number 5 written on it.

"Yes, exactly. Now, 3 is less than 5, so what do we change right to?"

"Mid?"

Robert bobbed up and down in affirmation. Sunny updated the table and wrote "0" for left and "3" for right.

Then she updated mid, which pointed to index 1 now. "It points to 2." Sunny looked at the pink pig.

"Yes, and 2 is the value we were looking for, so we're done. Does that make sense?"

"I suppose so." Sunny got the overall concept of halving the search area, at least.

Robert swept the magnetic strips away. "Great. Now then, you should learn about prefix sums."

Sunny bit her lip. More new concepts? She knew being a hero wasn't easy, but couldn't they have a stretch break, at least?

She was about to ask for a five minute break when the TV flickered on again.

A reporter appeared, standing in a field with workers moving books behind her. "Breaking news!" she announced. "The books recently stolen from the Method City Public Library were recovered here, a field near Parentheses Town." She tucked a curl of dark hair behind her ear while she gestured to the grass that was currently covered by hundreds of books.

Sunny gasped. "Robert, let's go!"

"Hold on. Look at what they're doing." Robert pointed at the trucks in the background. "Where else would they be moving the books but back to the library? We just need to wait."

"But– but what if they miss a book? We need to get that dark magic guide back."

Robert's pixelated eyes narrowed. "Shh."

Sunny was about to feel insulted at him shushing her when she realized the reporter had passed the mic to a police officer, who was holding up a large piece of wood.

On the wood was burned two sequences of numbers: 113, 230, 331, 448, 549 on top, then 99, 196, 311, 427, 535, 636 on the bottom.

"We found this code propped up next to the books. We are humbly requesting aid from the brightest minds in Javaland in cracking it."

Sunny sat up straighter.

"There will, of course, be a reward." The police officer paused for dramatic effect, then said, "Free debugging services for ten years!"

The reporter gasped. "Really? Well, you heard her, folks! Better get cracking on that code."

The police officer held up the board for a few more minutes, and Sunny scribbled the numbers down into her notebook. Then the TV screen fizzled back into blackness.

Sunny tapped her pencil against her chin. What could the numbers mean? Well, it looked like both sequences were increasing, and they were in the hundreds. "Robert, any ideas?"

The robot hovered closer to look at the notebook. "Well, whenever I see numbers, I think of the ASCII table. That's a table of all the number representations of different characters. For example, lowercase 'a' is represented as 97. But as far as I know, the ASCII table only goes up to 127…"

"Hmm." Sunny rotated the notebook upside down. "No luck there." She squinted at the numbers, just in case they were supposed to look like letters. "Nope."

"Shall we head to the library?" Robert asked. "Chances are, other codebreakers might be meeting there. Perhaps we can glean some insights."

Sunny nodded. "Let's get the guide back too."

With that, Sunny and Robert left the room and headed back to the Method City Public Library.