求给定数目的前 n 个素数

bool is_prime (const vector<int>& primes, int num)
{
    for (const auto& prime : primes) {
        if (num % prime == 0) {
            return false;
        }
    }
    return true;
}

vector<int32_t> get_primes (const int32_t& num)
{
    vector<int32_t> primes;
    primes.push_back (2);
    int32_t vec_size = 1;
    for (int32_t i = 3; vec_size != num; i += 2) {
        if (is_prime (primes, i)) {
            primes.push_back (i);
            ++vec_size;
        }
    }
    return move (primes);
}