Problem #10

Calculate the sum of all the primes below two million.

Inte så elegant lösning, transportsträcka.

#include <iostream>
#include <cmath>

template <typename T>
inline bool is_prime(T p)
{
  if (p == 1)
    return false;

  if (p == 2)
    return true;

  if (!(p & 1))
    return false;

  for (T i = 2; i < sqrt(p) + 1; ++i)
    if (!(p % i))
      return false;
  return true;
}

int main(int argc, char *argv[])
{
  uint64_t prime_sum = 0;
  for (uint64_t i = 0; i < 2000000; ++i)
    if (is_prime(i))
      prime_sum += i;
  std::cout << "Answer is " << prime_sum << std::endl;
  return 0;
}