private static long[] FindPrimes(long[] strongs, IPrimeDecider decider)
{
var list = new List <long>();
foreach (var number in strongs)
{
for (var digit = 1; digit < 10; digit += 2)
{
var newNumber = number.ToString().Plus(digit).ToLong();
if (newNumber.IsPrime(decider))
{
list.Add(newNumber);
}
}
}
return(list.ToArray());
}
private static bool IsStrong(long number, IPrimeDecider decider) => number.IsHarshad() && (number / number.SumDigits()).IsPrime(decider);
public static bool IsComposite(this long value, IPrimeDecider decider) => !decider.IsPrime(value);
public static bool IsPrime(this long value, IPrimeDecider decider) => decider.IsPrime(value);
