public double GetLongestConsecutivePrimeSum(int upto)
{
var primes = _eSieve.GetPrimes(upto).ToArray();
var maxSequence = 0;
int maxSequencePrime = 0;
// http://www.mathblog.dk/project-euler-50-sum-consecutive-primes/
var primeSums = GetPrimeSums(primes);
for (int i = 0; i < primes.Length - 1; i++)
{
for (int j = 2; j <= primes.Length; j++)
{
int sum = primeSums[j] - primeSums[i];
if (sum > upto)
{
break;
}
int rangeCount = j - i;
if (maxSequence < rangeCount &&
Array.BinarySearch(primes, sum) >= 0)
{
maxSequence = rangeCount;
maxSequencePrime = sum;
}
}
}
return(maxSequencePrime);
}
public void Run()
{
foreach (int prime in eSieve.GetPrimes(56003))
{
int length = DigitsCount(prime);
}
}
public string Run()
{
foreach (int prime in sieve.GetPrimes(1487))
{
int prime2 = prime + STEP;
int prime3 = prime + 2 * STEP;
if (sieve.IsPrime(prime2) && sieve.IsPrime(prime3))
{
List <int> digits1 = GetDigits(prime).ToList();
digits1.Sort();
List <int> digits2 = GetDigits(prime2).ToList();
digits2.Sort();
List <int> digits3 = GetDigits(prime3).ToList();
digits3.Sort();
bool isDesiredNumber = true;
for (int i = 0; i < digits1.Count; ++i)
{
if (digits1[i] != digits2[i] || digits2[i] != digits3[i] || digits1[i] != digits3[i])
{
isDesiredNumber = false;
break;
}
}
if (isDesiredNumber)
{
return(prime.ToString() + prime2.ToString() + prime3.ToString());
}
}
}
return(string.Empty);
}
public int Run(int maxNumber)
{
ESieve eSieve = new ESieve(maxNumber);
int[] primes = eSieve.GetPrimes().ToArray();
long[] primeSum = CalculateSums(primes).ToArray();
int maxLength = -1;
int desiredPrime = -1;
int i = 0;
while (i < primeSum.Length)
{
for (int j = i - (maxLength + 1); j >= 0; --j)
{
if (primeSum[i] - primeSum[j] > maxNumber)
{
break;
}
int sugestedPrime = (int)(primeSum[i] - primeSum[j]);
if (Array.BinarySearch(primes, sugestedPrime) > -1)
{
maxLength = i - j;
desiredPrime = sugestedPrime;
}
}
i++;
}
return(desiredPrime);
}
public int Run()
{
foreach (int prime in sieve.GetPrimes())
{
if (_checkedPrimes.Contains(prime))
{
continue;
}
CheckCircularPrime(prime);
}
return(_circularPrimes.Count());
}
public int Run()
{
int minSum = int.MaxValue;
foreach (int firstPrime in eSieve.GetPrimes())
{
if (firstPrime * 5 > minSum)
{
break;
}
foreach (int secondPrime in eSieve.GetPrimes(firstPrime))
{
if (firstPrime + secondPrime * 4 > minSum)
{
break;
}
if (!MakePrimes(firstPrime, secondPrime))
{
continue;
}
foreach (int thirdPrime in eSieve.GetPrimes(secondPrime))
{
if (firstPrime + secondPrime + thirdPrime * 3 > minSum)
{
break;
}
if (!MakePrimes(thirdPrime, secondPrime) || !MakePrimes(thirdPrime, firstPrime))
{
continue;
}
foreach (int fourthPrime in eSieve.GetPrimes(thirdPrime))
{
if (firstPrime + secondPrime + thirdPrime + fourthPrime * 2 > minSum)
{
break;
}
if (!MakePrimes(fourthPrime, thirdPrime) || !MakePrimes(fourthPrime, secondPrime) || !MakePrimes(fourthPrime, firstPrime))
{
continue;
}
foreach (int fifthPrime in eSieve.GetPrimes(fourthPrime))
{
if (firstPrime + secondPrime + thirdPrime + fourthPrime + fifthPrime > minSum)
{
break;
}
if (!MakePrimes(fifthPrime, fourthPrime) || !MakePrimes(fifthPrime, thirdPrime) ||
!MakePrimes(fifthPrime, secondPrime) || !MakePrimes(fifthPrime, firstPrime))
{
continue;
}
int sum = firstPrime + secondPrime + thirdPrime + fourthPrime + fifthPrime;
if (minSum > sum)
{
minSum = sum;
}
}
}
}
}
}
return(minSum);
}
public PrimeSummations()
{
_primeNumbers = _eSieve.GetPrimes(PRIME_COUNT).ToList();
}
public void TestGeneratingPrimes(int upto, int[] expected)
{
int[] actual = _sut.GetPrimes(upto).ToArray();
Assert.True(expected.SequenceEqual(actual));
}
