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>
       
#include <map>
       
 
       
int main()
       
{
       
  // prime numbers beyond this are not relevant for the problem
       
  const unsigned int MaxPrime = 2000000;
       
 
       
  // precompute all relevant prime numbers
       
  std::vector<unsigned int> primes;
       
  // the only even prime
       
  primes.push_back(2);
       
  // now check all odd numbers for primality
       
  for (unsigned int i = 3; i <= MaxPrime; i += 2)
       
  {
       
    bool isPrime = true;
       
    for (auto p : primes)
       
    {
       
      // no larger prime factor possible ?
       
      if (p*p > i)
       
        break;
       
 
       
      // no prime number ?
       
      if (i % p == 0)
       
      {
       
        isPrime = false;
       
        break;
       
      }
       
    }
       
 
       
    // yes, we have a new prime
       
    if (isPrime)
       
      primes.push_back(i);
       
  }
       
 
       
  // prime numbers were found in ascending order,
       
  // let's add their value and store in a map such that
       
  // [prime number] => [sum of all prime numbers up to the current]
       
  // note: long long is required to avoid overflows
       
  std::map<unsigned int, unsigned long long> sums;
       
  unsigned long long sum = 0;
       
  for (auto p : primes)
       
  {
       
    sum += p;
       
    sums[p] = sum;
       
  }
       
 
       
  // the test cases are more or less "smart" lookups
       
  unsigned int tests;
       
  std::cin >> tests;
       
  while (tests--)
       
  {
       
    unsigned int x;
       
    std::cin >> x;
       
 
       
    // find the closest prime number which is bigger than the input
       
    auto i = sums.upper_bound(x);
       
    // go back to the closest prime number which is smaller than the input
       
    i--;
       
 
       
    // show the sum associated to that prime number
       
    std::cout << i->second << std::endl;
       
  }
       
  return 0;
       
}

This solution contains 8 empty lines, 15 comments and 3 preprocessor commands.