public void IsSumOfFactorialOfDigits_Of145_ReturnsTrue()
{
// Arrange
var number = 145;
// Act
var result = FactorialHelper.IsSumOfFactorialOfDigits(number);
// Assert
result.Should().BeTrue();
}
public void Factorial_Of5_Returns120()
{
// Arrange
var n = 5;
var expectedResult = 120;
// Act
var result = FactorialHelper.Factorial(n);
// Assert
result.Should().Be(expectedResult);
}
public void BinominalCoefficient_Of4Over2_Returns6()
{
// Arrange
var n = 4;
var k = 2;
var expectedResult = 6;
// Act
var result = FactorialHelper.BinominalCoefficient(n, k);
// Assert
result.Should().Be(expectedResult);
}
private string GetNthLexiographicPermutation(BigInteger desiredIndex, List <char> orderedCharacters)
{
var numberOfCharacters = orderedCharacters.Count;
if (numberOfCharacters == 1)
{
return(ReturnCharacterIfDesiredIndexIs1(desiredIndex, orderedCharacters));
}
BigInteger currentIndex = 0;
int indexOfCharacterToUseNext = 0;
var numberOfWaysOtherCharacterCanBeOrderedWhenOneIsFixed = FactorialHelper.Factorial(numberOfCharacters - 1);
while (currentIndex + numberOfWaysOtherCharacterCanBeOrderedWhenOneIsFixed < desiredIndex)
{
currentIndex += numberOfWaysOtherCharacterCanBeOrderedWhenOneIsFixed;
indexOfCharacterToUseNext += 1;
}
var characterToUse = orderedCharacters[indexOfCharacterToUseNext];
var orderedDigitsWithoutDigitUsed = orderedCharacters.Where(character => character != characterToUse).ToList();
return(characterToUse.ToString() + GetNthLexiographicPermutation(desiredIndex - currentIndex, orderedDigitsWithoutDigitUsed));
}
private static void CalculateWithOperator(Stack stack, OperatorType operatorType)
{
double firstOperand;
double secondOperand;
switch (operatorType)
{
case OperatorType.Addition:
firstOperand = double.Parse(Convert.ToString(stack.Pop()));
secondOperand = double.Parse(Convert.ToString(stack.Pop()));
stack.Push(firstOperand + secondOperand);
break;
case OperatorType.Subtraction:
firstOperand = double.Parse(Convert.ToString(stack.Pop()));
secondOperand = double.Parse(Convert.ToString(stack.Pop()));
stack.Push(firstOperand - secondOperand);
break;
case OperatorType.Multiplication:
firstOperand = double.Parse(Convert.ToString(stack.Pop()));
secondOperand = double.Parse(Convert.ToString(stack.Pop()));
stack.Push(firstOperand * secondOperand);
break;
case OperatorType.Division:
firstOperand = double.Parse(Convert.ToString(stack.Pop()));
secondOperand = double.Parse(Convert.ToString(stack.Pop()));
if (firstOperand == 0)
{
throw new DivideByZeroException();
}
stack.Push(secondOperand / firstOperand);
break;
case OperatorType.Modulus:
firstOperand = double.Parse(Convert.ToString(stack.Pop()));
stack.Push(firstOperand / 100);
break;
case OperatorType.Pow:
firstOperand = double.Parse(Convert.ToString(stack.Pop()));
secondOperand = double.Parse(Convert.ToString(stack.Pop()));
if (secondOperand == 0 && firstOperand < 0)
{
throw new NotFiniteNumberException(secondOperand);
}
stack.Push(Math.Pow(secondOperand, firstOperand));
break;
case OperatorType.Factorial:
firstOperand = double.Parse(Convert.ToString(stack.Pop()));
stack.Push(FactorialHelper.CalculateFactorial(firstOperand));
break;
default:
throw new InvalidEnumArgumentException(nameof(operatorType), (int)operatorType, typeof(OperatorType));
}
}
public _53_CombinatoricSelections(int countGreaterThan)
{
_countGreaterThan = (uint)countGreaterThan;
_fHelper = new FactorialHelper();
}
public long ComputeSolution()
{
return((long)FactorialHelper.BinominalCoefficient(TOTAL_NUMBER_OF_STEPS, TOTAL_NUMBER_OF_STEPS_DOWNWARDS));
}
public long ComputeSolution()
{
var factorial = FactorialHelper.Factorial(NUMBER_TO_COMPUTE_FACTORIAL_OF);
return(NumberHelper.SumOfDigits(factorial));
}