My code

… was written in C++11 and can be compiled with G++, Clang++, Visual C++. You can download it, too. Or just jump to my GitHub repository.

       
#include <iostream>
       
#include <vector>
       
 
       
int main()
       
{
       
  // compute the first 10001 primes
       
  std::vector<unsigned int> primes;
       
  primes.reserve(10001);
       
  primes.push_back(2);
       
  for (unsigned int x = 3; primes.size() <= 10000; x += 2)
       
  {
       
    bool isPrime = true;
       
    for (auto p : primes)
       
    {
       
      // found a divisor ? => abort
       
      if (x % p == 0)
       
      {
       
        isPrime = false;
       
        break;
       
      }
       
 
       
      // no larger prime factors possible ?
       
      if (p*p > x)
       
        break;
       
    }
       
 
       
    // yes, we have a new prime
       
    if (isPrime)
       
      primes.push_back(x);
       
  }
       
 
       
  // processing all test cases is now just a plain lookup
       
  unsigned int tests;
       
  std::cin >> tests;
       
  while (tests--)
       
  {
       
      unsigned int x;
       
      std::cin >> x;
       
      // just look up the x-th prime
       
      // with a little twist: vector's index is zero-based, therefore "off by one"
       
      x--;
       
 
       
      if (x < primes.size())
       
        std::cout << primes[x] << std::endl;
       
      else
       
        std::cout << "ERROR" << std::endl;
       
  }
       
  return 0;
       
}

In order to run my code, execute
echo "1 10001" | ./euler-0007

(input format usually follows Hackerrank's requirements)

This solution contains 5 empty lines, 7 comments and 2 preprocessor commands.