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 Day14()
{
_map = new bool[128, 128];
for (int i = 0; i < 128; i++)
{
string hash = KnotHash.HashString($"{Seed}-{i}");
int col = 0;
foreach (char c in hash)
{
int num = c <= '9' ? c - '0' : c - 'a' + 10;
for (int bit = 3; bit >= 0; bit--)
{
_map[i, col++] = (num & (1 << bit)) != 0;
}
}
}
}
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()));
}
public void Part2()
{
string answer = KnotHash.HashString(_input);
Assert.Equal("541dc3180fd4b72881e39cf925a50253", answer);
}