/// <summary>
/// Gets the number of squares used for the specified key.
/// </summary>
/// <param name="key">The key to use to find the number of squares used.</param>
/// <returns>
/// The number of squares used for the specified key string.
/// </returns>
public static int GetSquaresUsed(string key)
{
int squaresUsed = 0;
for (int i = 0; i < 128; i++)
{
string input = $"{key}-{i}";
string knotHash = Day10.ComputeHash(input);
int[] numbers = knotHash
.Select((p) => Parse <int>(p.ToString(), NumberStyles.HexNumber))
.ToArray();
var bits = numbers
.Select((p) => BitConverter.GetBytes(p))
.Select((p) => new BitArray(p))
.ToArray();
squaresUsed += bits
.SelectMany((p) => p.OfType <bool>().Take(4))
.Where((p) => p)
.Count();
}
return(squaresUsed);
}
public static void Y2017_Day10_ComputeHash_Returns_Correct_Value(string asciiBytes, string expected)
{
// Act
string actual = Day10.ComputeHash(asciiBytes);
// Assert
actual.ShouldBe(expected);
}
