this post was submitted on 12 Dec 2025
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Advent Of Code

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An unofficial home for the advent of code community on programming.dev! Other challenges are also welcome!

Advent of Code is an annual Advent calendar of small programming puzzles for a variety of skill sets and skill levels that can be solved in any programming language you like.

Everybody Codes is another collection of programming puzzles with seasonal events.

EC 2025

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Day 12: Christmas Tree Farm

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[–] Pyro@programming.dev 3 points 1 week ago* (last edited 1 week ago) (5 children)

Python

You got me good, Eric.

hintThink of the simplest check you can make for a region.

click to view code

# This does not work for the sample :D

def solve(data: str):
    # split input
    blocks = data.split("\n\n")
    shape_blocks = blocks[:-1]
    region_block = blocks[-1]

    # for every shape, get the number of occupied cells
    shape_area = []
    for shape_block in shape_blocks:
        shape_area.append(shape_block.count('#'))

    fit_regions = 0

    # for every region, check if the area is sufficient to fit all shapes
    for region_data in region_block.splitlines():
        size_data, shape_data = region_data.split(': ')

        # get region size
        m, n = [int(dim) for dim in size_data.split('x')]

        # get area needed to fit all shapes, without considering arrangement
        area_needed = 0
        for id, freq in enumerate(map(int, shape_data.split(' '))):
            area_needed += shape_area[id] * freq
        
        # if the region area is sufficient, count it as a fit (!!!)
        if m * n > area_needed:
            fit_regions += 1
    
    return fit_regions

[–] CameronDev@programming.dev 2 points 1 week ago (1 children)

spoilerI had an feeling it would be trivial, but didnt think it would be that trivial. I got the answer without even parsing the shapes, just called them all 9.

[–] Pyro@programming.dev 2 points 1 week ago

Tap for spoilerThat's very interesting because that was one of my early approaches too, but it actually gave me the wrong answer for my input!

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