Problem #10

I had to make total a long long int to hold the value for this one hehe.

#include <iostream>
#include <ctime>
#include <cmath>

using namespace std;

bool isPrime (int);
 
int main(void) 
{
    clock_t start = clock();
    long long int total = 0;
    int holder = 0;

    while (holder < 2000000)
    {
        if (isPrime (holder))
            total += holder;
        holder++;
    }

    cout << total << endl 
         << "Process took " << (static_cast<double> (clock()) - start) / CLOCKS_PER_SEC << " seconds." << endl;
    system("pause");
    return 0;
}

bool isPrime (int num)
{
    if (num == 0 || num == 1)
        return false;
  
    if (num == 2 || num == 3)
        return true;

    for (unsigned int i = 2; i < static_cast<int> (sqrt (static_cast<double> (num))) + 1; i++)
        if (num % i == 0)
            return false;
   return true;
}