private static BigInteger Stirling_Calculate(BigInteger n, BigInteger k)
{
//(-1)^i(kCi)(k-i)^n = sum/k!
BigInteger constant = -1;
BigInteger i;
BigInteger sum = 0;
for (i = 0; i < k; i++)
{
//Console.WriteLine(PnC.PowerCalculator(constant, i) * PnC.nCr(k, i) * PnC.PowerCalculator(k-i, n));
sum = sum + (PnC.PowerCalculator(constant, i) * PnC.nCr(k, i) * PnC.PowerCalculator(k - i, n));
}
//sum/k factorial
return(sum / PnC.Factorial(k));
}
public void CombinationX() //COMBIX
{
base.CombinationXsign();
BigInteger n;
combiX_n:
Console.Write("Enter n: ", Color.White);
String inp = Console.ReadLine();
bool cont = true;
while (cont)
{
if (inp.Trim() == "" || inp == " ")
{
Console.Clear();
base.CombinationXsign();
Console.WriteLine("Value of 'n' should be greater than 0 and less than 500", Color.White);
goto combiX_n;
}
else if (reg.Match(inp).Success)
{
Console.Clear();
base.CombinationXsign();
Console.WriteLine("Value of 'n' should be greater than 0 and less than 500", Color.White);
goto combiX_n;
}
else
{
n = BigInteger.Parse(inp);
if (n <= 500 && n > 0)
{
break;
}
else
{
Console.Clear();
base.CombinationXsign();
Console.WriteLine("Value of 'n' should be greater than 0 and less than 500", Color.White);
goto combiX_n;
}
}
}
Console.Clear();
base.CombinationXsign();
n = BigInteger.Parse(inp);
BigInteger r;
Console.WriteLine("Value of n: " + n, Color.White);
combiX_r:
Console.Write("Enter r: ", Color.White);
String inp2 = Console.ReadLine();
while (cont)
{
if (inp2.Trim() == "" || inp2 == " ")
{
Console.Clear();
base.CombinationXsign();
Console.WriteLine("Value of n: " + n, Color.White);
Console.WriteLine("Value of 'r' should be less than 500 and 'n' should be greater or equal to 'r'", Color.White);
goto combiX_r;
}
else if (reg.Match(inp2).Success)
{
Console.Clear();
base.CombinationXsign();
Console.WriteLine("Value of n: " + n, Color.White);
Console.WriteLine("Value of 'r' should be less than 500 and 'n' should be greater or equal to 'r'", Color.White);
goto combiX_r;
}
else
{
r = BigInteger.Parse(inp2);
if (r <= 500 && n >= r)
{
break;
}
else
{
Console.Clear();
base.CombinationXsign();
Console.WriteLine("Value of n: " + n, Color.White);
Console.WriteLine("Value of 'r' should be less than 500 and 'n' should be greater or equal to 'r'", Color.White);
goto combiX_r;
}
}
}
r = BigInteger.Parse(inp2);
Console.Clear();
base.CombinationXsign();
Console.WriteLine("Value of n: " + n, Color.White);
Console.WriteLine("Value of r: " + r, Color.White);
Console.Write("Combination of " + n + " and " + r + " without repetition is: ", Color.White);
Console.Write(String.Format("{0:#,##0}", PnC.nCr(n, r)), Color.IndianRed);
Console.WriteLine();
Choice();
}
