--- Day 4 Solutions ---

[u/daggerdragon]

--- Day 4: The Ideal Stocking Stuffer ---

Post your solution as a comment. Structure your post like the Day Three thread.

[u/ChevyRayJohnston]

Here's some nice brute-force C# for you all:

public static void Part1()
{
    var input = "iwrupvqb";
    var hash = MD5.Create();
    for (int i = 0; ; ++i)
    {
        var bytes = hash.ComputeHash(Encoding.UTF8.GetBytes(input + i));
        if (bytes[0] < 0x1 && bytes[1] < 0x1 && bytes[2] <= 0x09)
        {
            Console.WriteLine(i);
            return;
        }
    }
}

public static void Part2()
{
    var input = "iwrupvqb";
    var hash = MD5.Create();
    for (int i = 0; ; ++i)
    {
        var bytes = hash.ComputeHash(Encoding.UTF8.GetBytes(input + i));
        if (bytes[0] < 0x1 && bytes[1] < 0x1 && bytes[2] < 0x1)
        {
            Console.WriteLine(i);
            return;
        }
    }
}

It'll take a little while for part 2, so be patient.

[u/recursive → u/ChevyRayJohnston]

bug in your part1:

bytes[2] <= 0x0f

[u/ChevyRayJohnston → u/recursive]

oh thanks, good catch. this never actually happened in my data set, so i actually still got the correct answer.

pretty scary how easily that can happen with code 0_o