title: Sum Subsets Set Formed First N Natural Numbers
signature: class Solution {
  
      public decimal SumSubsetsSetFormedFirstNNaturalNumbers(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(decimal actual, decimal expected){
              return Math.Abs(actual - expected) < 1e-09m;
          }
  
          public string driver(int n, decimal expected){
              try{
                PLACEHOLDER_CLS_NAME solution_cls = new PLACEHOLDER_CLS_NAME();
                decimal 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(
                  26, 
                  11777605632.0m
              );
              Console.WriteLine(string.Format(
                  "TEST-0...{0}",
                  result)
              );result = runner.driver(
                  35, 
                  10823317585920.0m
              );
              Console.WriteLine(string.Format(
                  "TEST-1...{0}",
                  result)
              );result = runner.driver(
                  34, 
                  5111011082240.0m
              );
              Console.WriteLine(string.Format(
                  "TEST-2...{0}",
                  result)
              );result = runner.driver(
                  22, 
                  530579456.0m
              );
              Console.WriteLine(string.Format(
                  "TEST-3...{0}",
                  result)
              );result = runner.driver(
                  3, 
                  24.0m
              );
              Console.WriteLine(string.Format(
                  "TEST-4...{0}",
                  result)
              );result = runner.driver(
                  25, 
                  5452595200.0m
              );
              Console.WriteLine(string.Format(
                  "TEST-5...{0}",
                  result)
              );result = runner.driver(
                  22, 
                  530579456.0m
              );
              Console.WriteLine(string.Format(
                  "TEST-6...{0}",
                  result)
              );
          }
      }
  }
  
source_py: def sum_subsets_set_formed_first_n_natural_numbers(n):
      return (((n * (n + 1)) / 2) * (1 << (n - 1)))
source_cpp: unsigned long long sum_subsets_set_formed_first_n_natural_numbers(int n) {
    return ( n * ( n + 1 ) / 2 ) * ( 1 << ( n - 1 ) );
  }