public void Part1()
{
int[] lengths = _input.Split(',').Select(int.Parse).ToArray();
KnotHash hash = new KnotHash(256);
foreach (int length in lengths)
{
hash.Apply(length);
}
int answer = hash.Enumerate().Take(2).Aggregate((x, y) => x * y);
Assert.Equal(23715, answer);
}
public static string HashString(string input, int size = 256)
{
int[] lengths = input.Select(c => (int)c).Concat(new[] { 17, 31, 73, 47, 23 }).ToArray();
KnotHash hash = new KnotHash(size);
for (int i = 0; i < 64; i++)
{
foreach (int length in lengths)
{
hash.Apply(length);
}
}
return(hash.Enumerate()
.Chunk(16)
.Select(chunk => chunk.Aggregate((x, y) => x ^ y))
.Select(n => string.Format("{0:x2}", n))
.Aggregate(new StringBuilder(), (sb, s) => sb.Append(s), sb => sb.ToString()));
}