this post was submitted on 12 Dec 2024
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Advent Of Code

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An unofficial home for the advent of code community on programming.dev!

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.

AoC 2024

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Day 12: Garden Groups

Megathread guidelines

  • Keep top level comments as only solutions, if you want to say something other than a solution put it in a new post. (replies to comments can be whatever)
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[โ€“] [email protected] 2 points 1 month ago

hey thanks!

I didn't check any other solutions before finishing (currently wondering way day 13 is too low), but I thought that trying to traverse fences would be a pain and since I have everything separated by regions and not traversing the array, counting corners never came to mind.

But the thought that I had was that for each region, all points will be a straight line in the V or H orientations, so if I can go up and down and count when last != next - 1, then that'll tell me that that is a contiguous piece of fence.

The idea isn't too hard, for tracking the XAxis it's

region.GroupBy(YAxis) // row
.Select(group => 
    group.Sort(g => g.XAxis) // column
        .Window(a,b => a != b - 1 ? 1 : 0).Sum()
.Sum()

Except that I used a different splitting method and that came to me later.