public void Run()
{
int a = -999, b = -999;
long testILongInt = 0;
long maxConsecutivePrimes = 0, maxACoefficient = 0, maxBCoefficient = 0;
for (int i = a; i <= 999; i++)
{
for (int j = b; j <= 999; j++)
{
int n = 0, consecutivePrimes = 0;
while (true)
{
testILongInt = GetQuadratic(i, j, n++);
if (testILongInt > 0 && Primes.IsPrime(testILongInt))
{
consecutivePrimes++;
}
else
{
if (consecutivePrimes > maxConsecutivePrimes)
{
maxConsecutivePrimes = consecutivePrimes;
maxACoefficient = i;
maxBCoefficient = j;
}
break;
}
}
}
}
this.result = (maxACoefficient * maxBCoefficient).ToString();
}
public long GetLengthWhereRationBelow(int percent)
{
long antallPrimetallFunnet = 0;
long step = 0;
long len = 1;
long counter = 0;
long current = 1;
while (true)
{
counter++;
//side komplett,sjekk ration
if (counter % 4 == 1)
{
if (counter > 1 && antallPrimetallFunnet * 10 < counter)
{
break;
}
//øk steg og sidelengde
step += 2;
len += 2;
}
current += step;
if (Primes.IsPrime(current, primliste))
{
antallPrimetallFunnet++;
}
}
return(len);
}
public Fraction GetRatio(int sidelength)
{
long isPrime = 0;
long start = 1;
long step = 0;
long len = 1;
long counter = 0;
long current = start;
while (len <= sidelength)
{
counter++;
if (counter % 4 == 1)
{
step += 2;
len += 2;
}
current = current + step;
if (Primes.IsPrime(current, primliste))
{
isPrime++;
}
}
return(new Fraction {
Numerator = isPrime, Denominator = counter
});
}
public long GetSmallestOddCompisteNotSum()
{
bool goldbachsotherconjecture = true;
long i = 1;
while (goldbachsotherconjecture)
{
i += 2;
if (!Primes.IsPrime(i))
{
bool thisgoldbachsotherconjecture = false;
long j = 1;
long rest = i - 2 * j * j;
while (!thisgoldbachsotherconjecture && rest > 0)
{
if (Primes.IsPrime(rest))
{
thisgoldbachsotherconjecture = true;
}
j++;
rest = i - 2 * j * j;
}
goldbachsotherconjecture = thisgoldbachsotherconjecture;
}
}
return(i);
}
public override object Run(RunModes runMode, object input, bool Logging)
{
Primes.InitPrimes();
int i = 9;
while (true)
{
bool foundOddComposite = false;
if (Primes.IsPrime(i))
{
i += 2; continue;
}
long sqrt = (long)Math.Sqrt(i);
for (int j = 1; j < sqrt; j++)
{
long diff = i - 2 * j * j;
if (Primes.IsPrime(diff))
{
foundOddComposite = true;
break;
}
}
if (!foundOddComposite)
{
return(i);
}
i += 2;
}
}
static bool CanStick(long n1, long n2)
{
if (n1 == n2)
{
return(false);
}
if (n2 < n1)
{
return(CanStick(n2, n1));
}
byte cachedValue = _stickCache[n1][n2];
if (cachedValue == CAN_STICK)
{
return(true);
}
if (cachedValue == CAN_NOT_STICK)
{
return(false);
}
_stickChecks++;
// Test n1 followed by n2
long m2 = GetDigitCountAsMultOfTen(n2);
long n = n2 + m2 * 10 * n1;
if (!_primes.IsPrime(n))
{
_stickCache[n1][n2] = CAN_NOT_STICK;
return(false);
}
// Test n2 followed by n1
long m1 = GetDigitCountAsMultOfTen(n1);
n = n1 + m1 * 10 * n2;
if (!_primes.IsPrime(n))
{
_stickCache[n1][n2] = CAN_NOT_STICK;
return(false);
}
else
{
_stickCache[n1][n2] = CAN_STICK;
return(true);
}
}
private long GetNextPrime(long next, List <long> listPrimeNumber)
{
while (!Primes.IsPrime(next, listPrimeNumber))
{
next++;
}
return(next);
}
public void Run()
{
SortedSet <long> primes = new SortedSet <long>();
SortedSet <long> generatedComposites = new SortedSet <long>();
SortedSet <long> composites = new SortedSet <long>();
int batchStart = 0, batchLength = 100;
long topPrime = 0, topComposite = 3;
while (true)
{
for (long i = batchStart; i < batchStart + batchLength; i++)
{
if (Primes.IsPrime(i))
{
primes.Add(i);
topPrime = i;
}
}
for (long i = topComposite; i < topPrime; i++)
{
if (i % 2 != 0 && !primes.Contains(i))
{
composites.Add(i);
topComposite = i;
}
}
foreach (long prime in primes)
{
long generatedComposite = 0;
int baseInt = 1;
while (generatedComposite < topPrime)
{
generatedComposite = GenerateComposite(prime, baseInt++);
if (!generatedComposites.Contains(generatedComposite))
{
generatedComposites.Add(generatedComposite);
}
}
}
foreach (long composite in composites)
{
if (!generatedComposites.Contains(composite))
{
this.result = composite.ToString();
return;
}
}
composites.Clear();
batchStart += batchLength;
}
}
public void Run()
{
int step = 2;
long currentInt = 3;
long countPrimes = 1;
long diagonals = 1;
int sideLength = 1;
float ratio = 100f;
Direction current = Direction.Left;
while (ratio > 10)
{
switch (current)
{
case Direction.Up:
step = step + 2;
break;
case Direction.Left:
case Direction.Right:
case Direction.Down:
default:
break;
}
currentInt += step;
if (currentInt != 2 && Primes.IsPrime(currentInt))
{
countPrimes++;
}
if (current == Direction.Right)
{
diagonals += 4;
ratio = (float)100 * (float)countPrimes / (float)diagonals;
sideLength += 2;
}
if (current != Direction.Up)
{
current++;
}
else
{
current = Direction.Left;
}
}
this.result = sideLength.ToString();
}
public override object Run(RunModes runMode, object input, bool Logging)
{
var signs = new List <int> {
1, -1
};
var max = (int)input;
Primes.InitPrimes(max);
var bPrimes = Primes.AllPrimes;
var maxIndex = 0;
var maxProduct = new QuadraticCoefficients(0, 0);
Primes.InitPrimes(80 * 80 + 80 * 1000 + 1000);
var SquareHash = new Dictionary <int, long>();
for (int i = 0; i <= max; i++)
{
SquareHash.Add(i, (long)Math.Pow(i, 2));
}
for (int a = -1 * max + 1; a < max; a += 2)
{
foreach (var prime in bPrimes)
{
foreach (var sign in signs)
{
var b = prime * sign;
bool isPrime;
var tempIndex = 0;
do
{
var quad = SquareHash[tempIndex] + tempIndex * a + b;
tempIndex++;
isPrime = Primes.IsPrime(quad);
} while (isPrime);
if (tempIndex > maxIndex)
{
maxIndex = tempIndex;
maxProduct = new QuadraticCoefficients(a, (int)b);
}
}
}
}
if (Logging)
{
Console.WriteLine(String.Format("{0}:{1}", maxProduct.A, maxProduct.B));
}
return(maxProduct.A * maxProduct.B);
}
public long SumOfStrongRightTruncatableHarshadPrimes(long max)
{
long sum = 0;
prinmeListe = Primes.GetPrimeFactorsBelowNumber((long)Math.Sqrt(902200000800800));
var file = File.CreateText(@"c:\temp\HarshadNumbers.txt");
List <long> rightTruncatableHarshadNumbers = new List <long>();
//finn rightTruncatableHarshadNumber melloem 10 og 100
for (int n = 10; n < 100; n++)
{
if (IsRightTruncatableHarshadNumber(n))
{
rightTruncatableHarshadNumbers.Add(n);
}
}
for (int p = 1; p < max - 1; p++)
{
List <long> nextRightTruncatableHarshadNumbers = new List <long>();
// 'left'-expand de kjente TruncatableHarshad nummerne
foreach (var n in rightTruncatableHarshadNumbers)
{
for (int i = 0; i < 10; i++)
{
//left...
long t = n * 10 + i;
if (IsStrongHarshadNumber(n) && Primes.IsPrime(t, prinmeListe))
{
sum += t;
file.WriteLine(t.ToString());
}
//til neste 'runde'
if (IsRightTruncatableHarshadNumber(t))
{
nextRightTruncatableHarshadNumbers.Add(t);
}
}
}
rightTruncatableHarshadNumbers = nextRightTruncatableHarshadNumbers;
}
file.Close();
return(sum);
}
public void Run()
{
for (int i = 999999999; i > 0; i--)
{
if (i % 2 != 0 && i % 10 != 0 && i % 3 != 0 &&
i % 5 != 0 && i % 7 != 0 &&
MathUtils.IsPandigital(i) &&
Primes.IsPrime(i))
{
this.result = i.ToString();
break;
}
}
}
public void Solve()
{
_found = false;
for (var i = 1000; i < 10000; i++)
{
IsPrime[i - 1000] = Primes.IsPrime(i);
}
for (var i = 1000; i < 10000; i++)
{
if (i != 1487 && IsPrime[i - 1000])
{
var d0 = i % 10;
var d1 = (i % 100) / 10;
var d2 = (i % 1000) / 100;
var d3 = i / 1000;
var second =
Try(i, d3, d2, d0, d1) +
Try(i, d3, d0, d2, d1) +
Try(i, d3, d1, d2, d0) +
Try(i, d3, d1, d0, d2) +
Try(i, d3, d0, d1, d2) +
Try(i, d2, d3, d1, d0) +
Try(i, d2, d3, d0, d1) +
Try(i, d0, d3, d2, d1) +
Try(i, d1, d3, d2, d0) +
Try(i, d1, d3, d0, d2) +
Try(i, d0, d3, d1, d2) +
Try(i, d2, d0, d3, d1) +
Try(i, d2, d1, d3, d0) +
Try(i, d0, d2, d3, d1) +
Try(i, d1, d2, d3, d0) +
Try(i, d0, d1, d3, d2) +
Try(i, d1, d0, d3, d2) +
Try(i, d2, d1, d0, d3) +
Try(i, d2, d0, d1, d3) +
Try(i, d1, d2, d0, d3) +
Try(i, d0, d2, d1, d3) +
Try(i, d1, d0, d2, d3) +
Try(i, d0, d1, d2, d3);
if (second != 0)
{
var third = 2 * second - i;
WriteLine(i * 100000000L + second * 10000L + third);
}
}
}
}
public bool IsStrongRightTruncatableHarshadPrimes(long number)
{
prinmeListe = Primes.GetPrimeFactorsBelowNumber((long)number);
long rest = number / 10;
if (IsRightTruncatableHarshadNumber(rest) &&
IsStrongHarshadNumber(rest) &&
Primes.IsPrime(number, prinmeListe)
)
{
return(true);
}
else
{
return(false);
}
}
public void IsPrime()
{
for (int i = 1; i <= 100; i++)
{
Test(i);
}
Test(1000000000037); // 10^12
Test(1000000000039);
Test(1L << 40);
Test((1L << 40) - 1);
void Test(long n)
{
Assert.AreEqual(Primes.Factorize(n).Length == 1, Primes.IsPrime(n));
}
}
private int SumOfAmicableParis(int input, bool Logging)
{
Primes.InitPrimes(input);
for (int i = 2; i < input; i++)
{
if (Primes.IsPrime(i))
{
continue;
}
int sumFactorsI;
int sumFactorsAmicableI;
if (_LongToSumOfProperFactorsHash.ContainsKey(i))
{
sumFactorsI = _LongToSumOfProperFactorsHash[i];
}
else
{
sumFactorsI = (int)Factors.SumFactors(i, true);
_LongToSumOfProperFactorsHash.Add(i, sumFactorsI);
}
if (_LongToSumOfProperFactorsHash.ContainsKey(sumFactorsI))
{
sumFactorsAmicableI = _LongToSumOfProperFactorsHash[sumFactorsI];
}
else
{
sumFactorsAmicableI = (int)Factors.SumFactors(sumFactorsI, true);
_LongToSumOfProperFactorsHash.Add(sumFactorsI, sumFactorsAmicableI);
}
if (i == sumFactorsAmicableI && i != sumFactorsI)
{
if (!_AmicableNumbers.Contains(i))
{
_AmicableNumbers.Add(i);
_AmicableNumbers.Add(sumFactorsI);
}
}
}
return(_AmicableNumbers.Sum());
}
public bool IsConcatenatingPrimes(long prime1, long prime2)
{
string s1 = prime1.ToString() + prime2.ToString();
long p1 = long.Parse(s1);
if (Primes.IsPrime(p1, primliste))
{
s1 = prime2.ToString() + prime1.ToString();
p1 = long.Parse(s1);
if (Primes.IsPrime(p1, primliste))
{
return(true);
}
}
return(false);
}
public void Run()
{
long i = 0;
// Generate primes up to half te current
for (i = 0; i < 323; i++)
{
if (Primes.IsPrime(i))
{
primes.Add(i);
}
}
long currInt = 646;
int currCount = 0;
while (true)
{
if ((currInt + 1) % 2 == 0)
{
if (Primes.IsPrime(++i))
{
primes.Add(i);
}
}
if (IsDivisibleByFourPrimes(++currInt))
{
currCount++;
}
else
{
currCount = 0;
}
if (currCount == 4)
{
this.result = (currInt - 3).ToString();
return;
}
}
}
private bool RecurivePerm(int number, int[] availableNumberlist, int currentLevel)
{
if (availableNumberlist.Length == 1)
{
if (Primes.IsPrime(number * 10 + availableNumberlist[0]))
{
LargestPandigitalPrime = number * 10 + availableNumberlist[0];
return(true);
}
return(false);
}
foreach (int nextAviableNumber in availableNumberlist)
{
if (RecurivePerm(number * 10 + nextAviableNumber, availableNumberlist.Where(e => e != nextAviableNumber).ToArray(), currentLevel + 1))
{
return(true);
}
}
return(false);
}
public void Sample()
{
// 素因数分解
Console.WriteLine(string.Join(" * ", Primes.Factorize(2020)));
// 2 * 2 * 5 * 101
// 約数の列挙
Console.WriteLine(string.Join(" ", Primes.Divisors(2020)));
// 1 2 4 5 10 20 101 202 404 505 1010 2020
// 素数判定
Console.WriteLine(Primes.IsPrime(1000000007));
// True
// n 以下の素数の列挙
Console.WriteLine(string.Join(" ", Primes.GetPrimes(100)));
// 2 3 5 7 11 13 17 19 23 29 31 37 41 43 47 53 59 61 67 71 73 79 83 89 97
// m 以上 M 以下の素数の列挙
Console.WriteLine(string.Join(" ", Primes.GetPrimes(1000000000, 1000000100)));
// 1000000007 1000000009 1000000021 1000000033 1000000087 1000000093 1000000097
}
public void Solve()
{
var cPrimes = 0;
var corner = 1;
for (var side = 3; side < int.MaxValue; side += 2)
{
var inc = side - 1;
cPrimes +=
(Primes.IsPrime(corner + inc) ? 1 : 0) +
(Primes.IsPrime(corner + 2 * inc) ? 1 : 0) +
(Primes.IsPrime(corner + 3 * inc) ? 1 : 0) +
(Primes.IsPrime(corner + 4 * inc) ? 1 : 0);
if (10 * cPrimes < 2 * side - 1)
{
WriteLine(side);
break;
}
corner += 4 * inc;
}
}
private bool IsTruncatablePrime(int currNumber)
{
string numStr = currNumber.ToString();
string subSrtRight = "", subSrtLeft = "";
for (int i = 1; i <= numStr.Length; i++)
{
subSrtRight = numStr.Substring(numStr.Length - i);
if (!Primes.IsPrime(Int32.Parse(subSrtRight)))
{
return(false);
}
subSrtLeft = numStr.Substring(0, i);
if (!Primes.IsPrime(Int32.Parse(subSrtLeft)))
{
return(false);
}
}
Console.WriteLine("Both ways truncatable prime:" + currNumber);
return(true);
}
public void Run()
{
int circPrimes = 0;
for (int i = 2; i < 1000000; i++)
{
bool isFullPrime = true;
foreach (int num in MathUtils.NumberRotations(i))
{
if (!Primes.IsPrime(num))
{
isFullPrime = false;
break;
}
}
if (isFullPrime)
{
circPrimes++;
}
}
this.result = circPrimes.ToString();
}
// A Harshad or Niven number is a number that is divisible by the sum of its digits.
private bool IsStrongHarshadNumber(long number)
{
long sum = DigitSum(number);
return(number % sum == 0 && Primes.IsPrime(number / sum, prinmeListe));
}
public void ReturnsFalseGivenValuesLessThan2(ulong number)
{
bool result = Primes.IsPrime(number);
Assert.False(result, number.ToString() + " should not be prime");
}
public void RecognizesCompositeNumbers(ulong number)
{
bool result = Primes.IsPrime(number);
Assert.False(result, number.ToString() + " should not be prime");
}
public void RecognizesPrimeNumbers(ulong number)
{
bool result = Primes.IsPrime(number);
Assert.True(result, number.ToString() + " should be prime");
}
public void Run()
{
for (int i = 1000; i < 10000; i++)
{
if (Primes.IsPrime(i))
{
byte[] bytes =
{
Byte.Parse(i.ToString()[0].ToString()),
Byte.Parse(i.ToString()[1].ToString()),
Byte.Parse(i.ToString()[2].ToString()),
Byte.Parse(i.ToString()[3].ToString()),
};
List <byte[]> permutations = CombiUtils.IntCombinations(bytes, 4);
List <int> primes = new List <int>();
List <int> solutionPrimes = new List <int>();
foreach (byte[] perm in permutations)
{
int prime = Int32.Parse(bytesToString(perm));
if (Primes.IsPrime(prime))
{
primes.Add(prime);
}
}
primes.Sort();
primes = primes.Where(x => x.ToString().Length == 4).ToList();
for (int firstIndex = 0; firstIndex < primes.Count(); firstIndex++)
{
bool found = false;
int secondIndex = 1;
while (secondIndex < primes.Count())
{
int diff = primes[secondIndex] - primes[firstIndex];
for (int l = primes.Count - 1; l > secondIndex; l--)
{
if (diff == primes[l] - primes[secondIndex] && diff != 0)
{
solutionPrimes.Add(primes[firstIndex]);
solutionPrimes.Add(primes[secondIndex]);
solutionPrimes.Add(primes[l]);
found = true;
break;
}
}
if (found)
{
break;
}
secondIndex++;
}
if (found)
{
break;
}
}
if (solutionPrimes.Count == 3)
{
if (solutionPrimes[1] - solutionPrimes[0] == solutionPrimes[2] - solutionPrimes[1])
{
Console.WriteLine("Prime 1: {0} Prime 2: {1} Prime 3: {2} - Diff value: {3}",
solutionPrimes[0],
solutionPrimes[1],
solutionPrimes[2],
solutionPrimes[2] - primes[1]
);
}
if (solutionPrimes[0] != 1487)
{
this.result = solutionPrimes[0] + "" + solutionPrimes[1] + "" + solutionPrimes[2];
return;
}
}
}
}
}
public void IsPrime_ValidValues_ReturnsIfValueIsPrime(int testValue, bool expectedResult)
{
bool result = Primes.IsPrime(testValue);
Assert.That(result, Is.EqualTo(expectedResult));
}
public void IsPrime_ShouldBeTrueForPrimesOnly(long number, bool expectedValue)
{
bool value = Primes.IsPrime(number);
Assert.AreEqual(expectedValue, value);
}