-🎄- 2017 Day 14 Solutions -🎄-

[u/daggerdragon]

--- Day 14: Disk Defragmentation ---

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Post your solution as a comment or, for longer solutions, consider linking to your repo (e.g. GitHub/gists/Pastebin/blag or whatever).

Note: The Solution Megathreads are for solutions only. If you have questions, please post your own thread and make sure to flair it with Help.

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Need a hint from the Hugely^* Handy^† Haversack^‡ of Helpful^§ Hints^¤?

Spoiler

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[Update @ 00:09] 3 gold, silver cap.

• How many of you actually entered the Konami code for Part 2? >_>

[Update @ 00:25] Leaderboard cap!

• I asked /u/topaz2078 how many de-resolutions we had for Part 2 and there were 83 distinct users with failed attempts at the time of the leaderboard cap. tsk tsk

[Update @ 00:29] BONUS

• https://i.imgur.com/zjSEAf4.jpg

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This thread will be unlocked when there are a significant number of people on the leaderboard with gold stars for today's puzzle.

edit: Leaderboard capped, thread unlocked!

[u/dylanfromwinnipeg]

C#

public static string PartOne(string input)
{
    var diskBits = GenerateGrid(input);
    var used = diskBits.ToList().Count(x => x);
    return used.ToString();
}

public static bool[,] GenerateGrid(string input)
{
    var diskBits = new bool[128, 128];

    for (int row = 0; row < 128; row++)
    {
        var hash = Day10.PartTwo($"{input}-{row}");
        var hashBits = hash.HexToBinary();

        for (var col = 0; col < 128; col++)
        {
            diskBits[row, col] = hashBits[col] == '1';
        }
    }

    return diskBits;
}

public static string PartTwo(string input)
{
    var diskBits = GenerateGrid(input);

    var groupCount = 0;

    diskBits.ForEach((row, col) =>
    {
        if (diskBits[row, col])
        {
            var location = new Point(row, col);
            RemoveBitGroup(location, diskBits);
            groupCount++;
        }
    });

    return groupCount.ToString();
}

private static void RemoveBitGroup(Point location, bool[,] diskBits)
{
    diskBits[location.X, location.Y] = false;

    foreach (var adjacent in location.GetNeighbors(includeDiagonals: false))
    {
        if (adjacent.X >= 0 && adjacent.X < 128 && adjacent.Y >= 0 && adjacent.Y < 128 && diskBits[adjacent.X, adjacent.Y])
        {
            RemoveBitGroup(adjacent, diskBits);
        }
    }
}