In that loop , I am collecting all the primes in vector how ever I changed the c++ code and now it resembles to Haskell code. This code still gives the answer within a second.

#include<cstdio>
#include<iostream>
#include<vector>
#define Lim 100000001
using namespace std;

bool prime [Lim];
vector<int> v ;

void isPrime ()
     {
        for( int i = 2 ; i * i <= Lim ; i++)
        if ( !prime [i]) for ( int j = i * i ; j <= Lim ; j += i ) prime [j] = 1 ;

        //for( int i = 2 ; i <= Lim ; i++) if ( ! prime[i] ) v.push_back( i ) ;
        //cout<<v.size()<<endl;
        //for(int i=0;i<10;i++) cout<<v[i]<<" ";cout<<endl;

     }

int main()
    {
        isPrime();
        int n = v.size();
        long long sum = 0;
        for(int i = 0 ; i < Lim ; i ++)
        if ( ! prime [i])
        {
            int k = i-1;
            bool f = 0;
            for(int i = 1 ; i*i<= k ; i++)
                if ( k % i == 0 && prime[ i + ( k / i ) ] ) { f=1 ; break ; }

            if ( !f ) sum += k;
        }
        cout<<sum<<endl;
    }

Regards
Mukesh Tiwari

On Tue, Nov 8, 2011 at 6:03 PM, Ivan Lazar Miljenovic <ivan.miljenovic@gmail.com> wrote:

On 8 November 2011 23:29, mukesh tiwari <mukeshtiwari.iiitm@gmail.com> wrote:
>> Also, I'm not sure if the logic in the two versions is the same: I'm
>> not sure about how you handle the boolean aspect in C++, but you have
>> a third for-loop there that doesn't seem to correspond to anything in
>> the Haskell version.
>>
> Which loop ?

for( int i = 2 ; i <= Lim ; i++) if ( ! prime[i] ) v.push_back( i ) ;

--
Ivan Lazar Miljenovic
Ivan.Miljenovic@gmail.com
IvanMiljenovic.wordpress.com