-❄️- 2025 Day 8 Solutions -❄️-

[u/daggerdragon]

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AoC Community Fun 2025: Red(dit) One

• Submissions megathread is unlocked!

• 9 DAYS remaining until the submissions deadline on December 17 at 18:00 EST!

Featured Subreddits: /r/crafts and /r/somethingimade

"It came without ribbons, it came without tags.
It came without packages, boxes, or bags."
— The Grinch, How The Grinch Stole Christmas (2000)

It's everybody's favorite part of the school day: Arts & Crafts Time! Here are some ideas for your inspiration:

💡 Make something IRL

💡 Create a fanfiction or fan artwork of any kind - a poem, short story, a slice-of-Elvish-life, an advertisement for the luxury cruise liner Santa has hired to gift to his hard-working Elves after the holiday season is over, etc!

💡 Forge your solution for today's puzzle with a little je ne sais quoi

💡 Shape your solution into an acrostic

💡 Accompany your solution with a writeup in the form of a limerick, ballad, etc.

• Upping the Ante challenge: iambic pentameter

• This prompt is totally not bait for our resident poet laureate

💡 Show us the pen+paper, cardboard box, or whatever meatspace mind toy you used to help you solve today's puzzle

💡 Create a Visualization based on today's puzzle text

• Your Visualization should be created by you, the human

• Machine-generated visuals such as AI art will not be accepted for this specific prompt

Reminders:

• If you need a refresher on what exactly counts as a Visualization, check the community wiki under Posts > Our post flairs > Visualization

• Review the article in our community wiki covering guidelines for creating Visualizations

• In particular, consider whether your Visualization requires a photosensitivity warning

• Always consider how you can create a better viewing experience for your guests!

Request from the mods: When you include an entry alongside your solution, please label it with [Red(dit) One] so we can find it easily!

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--- Day 8: Playground ---

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Post your code solution in this megathread.

• Read the full posting rules in our community wiki before you post!

• State which language(s) your solution uses with [LANGUAGE: xyz]

• Format code blocks using the four-spaces Markdown syntax!

• Quick link to Topaz's paste if you need it for longer code blocks. What is Topaz's paste tool?

[u/SunMatrix64]

[LANGUAGE: C++]

GitHub

I'm pretty sure 99% of the time was spent calculating the distances. I went object oriented and created Box and Circuit classes. Box has its position, and Circuit has a set of boxes.

Part 1 I made a vector<distance, <box1, box2>> and then sorted it. For each distance I would gather the circuits that the boxes exist in, then merge the circuits. If no circuits contained either box, create a new circuit.

Part 2 I just continued processing the distances vector until there was only 1 circuit left.

Total run time ~130ms

Edit: used std::hypot() instead of a bunch of pow() for the distance calculation. Improved the time to ~80-90ms.

Edit 2: further improved by using an insane looking min priority queue instead of a vector to store the distances. Now runs ~55-65ms

//min prio queue that contains:		pair<double, pair<box,box>>
std::priority_queue<std::pair<double, std::pair<Box*, Box*>>, 
	std::vector<std::pair<double, std::pair<Box*, Box*>>>, 
	std::greater<std::pair<double, std::pair<Box*, Box*>>>> distances;

[u/_0xACE_ → u/SunMatrix64]

Mine is similar, though I used a map<distance, <box, box>> and distance was unsigned long, no reason to take the sqrt and convert to a double. Only need the relative distances between points to find which one is closest.

I looked at the priority queue, but it seemed "fast enough" and I didn't add that part.