Unusual Speed Difference between Python and C++

Question

I recently wrote a short algorithm to calculate happy numbers in python. The program allows you to pick an upper bound and it will determine all the happy numbers below it.

Answer 1

Here's a C# version:

using System;
using System.Collections.Generic;
using System.Text;

namespace CSharp
{
  class Program
  {
    static void Main (string [] args)
    {
      while (true)
      {
        Console.Write ("Pick an upper bound: ");

        String
          input = Console.ReadLine ();

        uint
          upper_bound;

        if (uint.TryParse (input, out upper_bound))
        {
          DateTime
            start = DateTime.Now;

          CalcHappyNumbers (upper_bound);

          DateTime
            end = DateTime.Now;

          TimeSpan
            span = end - start;

          Console.WriteLine ("Time taken = " + span.TotalSeconds + " seconds.");
        }
        else
        {
          Console.WriteLine ("Error in input, unable to parse '" + input + "'.");
        }
      }
    }

    enum State
    {
      Happy,
      Sad,
      Unknown
    }

    static void CalcHappyNumbers (uint upper_bound)
    {
      SortedDictionary
        happy = new SortedDictionary ();

      SortedDictionary
        happy_numbers = new SortedDictionary ();

      happy [1] = State.Happy;
      happy_numbers [1] = true;

      for (uint current = 2 ; current < upper_bound ; ++current)
      {
        FindState (ref happy, ref happy_numbers, current);
      }

      //foreach (KeyValuePair pair in happy_numbers)
      //{
      //  Console.Write (pair.Key.ToString () + ", ");
      //}

      //Console.WriteLine ("");
    }

    static State FindState (ref SortedDictionary happy, ref SortedDictionary happy_numbers, uint value)
    {
      State
        current_state;

      if (happy.TryGetValue (value, out current_state))
      {
        if (current_state == State.Unknown)
        {
          happy [value] = State.Sad;
        }
      }
      else
      {
        happy [value] = current_state = State.Unknown;

        uint
          new_value = 0;

        for (uint i = value ; i != 0 ; i /= 10)
        {
          uint
            lsd = i % 10;

          new_value += lsd * lsd;
        }

        if (new_value == 1)
        {
          current_state = State.Happy;
        }
        else
        {
          current_state = FindState (ref happy, ref happy_numbers, new_value);
        }

        if (current_state == State.Happy)
        {
          happy_numbers [value] = true;
        }

        happy [value] = current_state;
      }

      return current_state;
    }
  }
}

I compared it against Dr_Asik's C++ code. For an upper bound of 100000 the C++ version ran in about 2.9 seconds and the C# version in 0.35 seconds. Both were compiled using Dev Studio 2005 using default release build options and both were executed from a command prompt.