Generating Bells number algorithm
algorithm, c#
Solution
use `BigInteger Structure` available in namespace `System.Numerics`
I think this would be useful to you
http://msdn.microsoft.com/en-us/library/system.numerics.biginteger.aspx
working with incredibly large numbers in .NET
http://www.codeproject.com/Articles/2728/C-BigInteger-Class
Problem
I am trying to generate nth bell number for large values between 500 to 1000. Bells number is huge and i can't store it in ulong. (To know bells number: http://en.wikipedia.org/wiki/Bell_number) I tried the triangular method to compute the number. Can any temme a way to save huge numbers like dat and perform the operation. Here is the Code i wrote ``` using System; class Program { static void Main(string[] args) { int length; do { length =-1; string numLength= Console.ReadLine(); if (int.TryParse(numLength, out length)) { Console.WriteLine("Sequence length is : {0}", TriangularMethod(length)); } }while(length>0); } static ulong TriangularMethod(int n) { Dictionary<long, List<ulong>> triangle = new Dictionary<long, List<ulong>>(); triangle.Add(1, new List<ulong>(new ulong[] { 1 })); for (int i = 2; i <= n; i++) { triangle.Add(i, new List<ulong>()); triangle[i].Add(triangle[i - 1].Last()); ulong lastVal = 0; for (int k = 1; k < i; k++) { lastVal = triangle[i][k - 1] + triangle[i - 1][k - 1]; triangle[i].Add(lastVal); } triangle.Remove(i - 2); } return triangle[n].Last(); } } ``` If there is a faster way to compute the same. please temme.