private bool IsValid(double sum)
{
// Keep only the last {COUNT_PREAMBLE} numbers
int sumIndex = Sums.IndexOf(sum);
var preambules = AllInputs.Skip(sumIndex).Take(COUNT_PREAMBLE);
// Cross join the preambules together then validate sum
var crossPreambules = preambules.SelectMany(x => preambules.Where(y => y != x), (x, y) => new { x, y }).ToList();
return(crossPreambules.Any((combo) => combo.x + combo.y == sum));
}
public bool IsDependentOn(string subjectIdentifier, string dependencyIdentifier)
{
if (subjectIdentifier is null || dependencyIdentifier is null || !AllInputs.Any())
{
return(false);
}
var subject = AllInputs.FirstOrDefault(x => x.OriginalIdentifier.EndsWith(subjectIdentifier));
var target = AllInputs.FirstOrDefault(x => x.OriginalIdentifier.EndsWith(dependencyIdentifier));
return(Dependencies[subject].Dependencies.Any(x => x.Input.OriginalIdentifier == target.OriginalIdentifier));
}
protected override void Run()
{
// Parse input string -> double
AllInputs = InputLines.Select(x => double.Parse(x)).ToList();
Sums = AllInputs.Skip(COUNT_PREAMBLE).ToList();
// Part 1: Check the one that is not valid
double susNumber = Sums.FirstOrDefault((sum) => !IsValid(sum));
AnswerPart1 = susNumber.ToString();
// Part 2: Calculate weakness of the not valid number
AnswerPart2 = CalculateWeakness(susNumber).ToString();
}
private double CalculateWeakness(double invalidNumber)
{
for (int i = 0; i < AllInputs.Count; i++)
{
double nb = AllInputs[i];
for (int j = i + 1; j < AllInputs.Count; j++)
{
nb += AllInputs[j];
if (nb == invalidNumber)
{
// Found weakness
List <double> weaknesses = AllInputs.Skip(i).Take(j - i).ToList();
return(weaknesses.Min() + weaknesses.Max());
}
}
}
throw new Exception("Weakness not found");
}
