title: Bell Numbers Number Of Ways To Partition A Set
signature: class Solution {
  
      public int BellNumbersNumberOfWaysToPartitionASet(int n) {
test_code: using System;
  using System.Numerics;
  using System.Diagnostics;
  using System.Collections.Generic;
  using System.Linq;
  using System.Text;
  using System.Security.Cryptography;
  using System.Web.UI;
  using System.Web.Script.Serialization;
  
  // SOLUTION CODE
  // ============================================
  PLACEHOLDER_CODE_BODY
  
  // TESTING CODE 
  // ============================================
  namespace EvaluatePrediction {
      class TestRunner {
          public bool ValidateSolution(int actual, int expected){
              return new JavaScriptSerializer().Serialize(actual) == new JavaScriptSerializer().Serialize(expected);
          }
  
          public string driver(int n, int expected){
              try{
                PLACEHOLDER_CLS_NAME solution_cls = new PLACEHOLDER_CLS_NAME();
                int pred_result = solution_cls.PLACEHOLDER_FN_NAME(n); 
                if (ValidateSolution(
                      pred_result,
                      expected)){
                  return "PASSED";
                }
                return "FAILED";
              } 
              catch (Exception exception_obj)
              {
                return exception_obj.GetType().FullName;
              }
          }
          static void Main(string[] args) {
              TestRunner runner = new TestRunner();
              String result;
              result = runner.driver(
                  9, 
                  21147
              );
              Console.WriteLine(string.Format(
                  "TEST-0...{0}",
                  result)
              );result = runner.driver(
                  4, 
                  15
              );
              Console.WriteLine(string.Format(
                  "TEST-1...{0}",
                  result)
              );result = runner.driver(
                  6, 
                  203
              );
              Console.WriteLine(string.Format(
                  "TEST-2...{0}",
                  result)
              );
          }
      }
  }
  
source_py: def bell_numbers_number_of_ways_to_partition_a_set(n):
      bell = [[0 for i in range((n + 1))] for j in range((n + 1))]
      bell[0][0] = 1
      for i in range(1, (n + 1)):
          bell[i][0] = bell[(i - 1)][(i - 1)]
          for j in range(1, (i + 1)):
              bell[i][j] = (bell[(i - 1)][(j - 1)] + bell[i][(j - 1)])
      return bell[n][0]
source_cpp: int bell_numbers_number_of_ways_to_partition_a_set(int n) {
    int bell [ n + 1 ] [ n + 1 ];
    bell [ 0 ] [ 0 ] = 1;
    for ( int i = 1;
    i <= n;
    i ++ ) {
      bell [ i ] [ 0 ] = bell [ i - 1 ] [ i - 1 ];
      for ( int j = 1;
      j <= i;
      j ++ ) bell [ i ] [ j ] = bell [ i - 1 ] [ j - 1 ] + bell [ i ] [ j - 1 ];
    }
    return bell [ n ] [ 0 ];
  }