Summation of primes | Project Euler | Problem #10

URL to the problem page: https://projecteuler.net/problem=10

The sum of the primes below 10 is 2 + 3 + 5 + 7 = 17.

Find the sum of all the primes below two million.

#include <iostream>

using namespace std;

int main()

{

    long long sum = 0, counter, i, j;

    for (i = 3; i < 2000000; i += 2) {

        counter = 0;

        for (j = 2; j <= sqrt(i); j++) {

            if (i % j == 0) {

                counter++;

                break;

            }

        }

        if (counter == 0) {

            sum += i;

        }

    }

    cout << "Sum of all the primes below 2.000.000 is  =  " << sum + 2 << endl;

    return 0;

}



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