AoC# 2024 - Day 12: Garden Groups

It’s Advent of Code time 🎄

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

Day 12 finds us pricing up some garden fencing…

Part 1 ⭐️

Pretty straightforward, though I had to look up the algorithm for a flood fill - turns out it’s not too dissimilar to the path-walking we did two days ago 🙂

Part 2 ⭐️

After a little refactoring so the Garden objects I’d created in Part 1 were also available to my Part 2 function, I just had to implement a Garden.Sides property…

public string Part1()
{
    return _gardens
        .Aggregate(0, (sum, garden) => sum += (garden.Area * garden.Perimeter))
        .ToString();
}

public string Part2()
{
    return _gardens
        .Aggregate(0, (sum, garden) => sum += (garden.Area * garden.Sides))
        .ToString();
}

My first attempt was a little naïve - a simple distinct of the top, bottom, left and right edge locations didn’t factor that the edges mightn’t be contiguous. A bit more thought and I had the example correct and my puzzle input answer correct too.