public double GetDivisiblePanDigitalNumberSum(string digits = "9876543210")
{
var results = StringPermutations.Permute(digits).Select(Convert.ToDouble)
.Where(d => TestValue(d.ToString())).ToList();
return(results.Sum());
}
//would probably work but not enough memory not to mention rather inefficient
//public int GetLargestPandigitalPrimeBelowNumber(int number = 987654322)
//{
// var primes = PrimeNumberHelper.GetPrimeNumbersBelowNumber(number);
// Func<int, bool> isPandigital = i =>
// {
// var digits = new Dictionary<string, int>();
// Enumerable.Range(1, 9)
// .Select(e => new KeyValuePair<string, int>(e.ToString(), 0))
// .ToList().ForEach(e => digits.Add(e.Key, e.Value));
// i.ToString().ToCharArray().ToList().ForEach(c => digits[c.ToString()] = digits[c.ToString()] + 1);
// return digits.All(d => d.Value < 2);
// };
// return primes.Where(isPandigital).Max();
//}
public int GetLargestPandigitalPrimeForDigits(string digits = "987654321")
{
var primes = new List <int>();
while (primes.Count == 0)
{
var results = StringPermutations.Permute(digits).Select(r => Convert.ToInt32(r)).ToList();
primes = results.Where(r => PrimeNumberHelper.IsPrime(r)).ToList();
digits = digits.Substring(1);
}
return(primes.Max());
}