math - Why is this Ruby code far faster than the equivalent C++ code? -

recently i've been going through easy project euler problems , solving them in ruby , c++. problem 14 concerning collatz conjecture, c++ code went on half hour before terminated it, though when translated code ruby, solved in 9 seconds.

that difference quite unbelievable me - had been led believe c++ faster ruby, mathematical process.

my code follows.

c++:

#include <iostream>  using namespace std;  int main () {     int = 2;     int b = 2;     int c = 0;     while (b < 1000000)     {          = b;         int d = 2;         while (a != 4)         {             if (a % 2 == 0)                 /= 2;             else                 = 3*a + 1;             d++;         }         if (d > c)         {             cout << b << ' ' << d << endl;             c=d;         }         b++;     }     cout << c;     return 0; } 

run time - don't know, it's really long time.

and ruby:

#!/usr/bin/ruby -w      = 0     b = 2     c = 0     while b < 1000000         = b;         d = 2         while != 4             if % 2 == 0                 /= 2             else                  = 3*a + 1             end             d+=1         end         if d > c             p b,d             c=d         end         b+=1     end     p c 

run time - approximately 9 seconds.

any idea what's going on here?

p.s. c++ code runs deal faster ruby code until hits 100,000.

you're overflowing int, it's not terminating. use int64_t instead of int in c++ code. you'll need include stdint.h that..