import java.util.ArrayList;
 
public class Main
{
  /**
   * The sum of the primes below 10 is 2 + 3 + 5 + 7 = 17
   * Find the sum of all the primes below two million.
   * @param args
   */
  public static void main(String[] args)
  {
    ArrayList<Integer> primes = new ArrayList<Integer>();
    int upper = 2000000;
    primes.ensureCapacity(upper);
    for (int i = 0; i < upper; i++)
    {
      primes.add(i);
    }
    long sum = 0;
    for (int i = 2; i <= upper / i; i++)
    {
      if ( primes.get(i) > 0 )
      {
        for (int k = i*i; k < upper ; k+=i)
        {
          primes.set(k,0);
        }
      }
    }
    for (int i = 2; i < upper; i++)
    {
      sum += primes.get(i);
    }
    System.out.println(sum);
  }
}

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

d2FzOiA0S0QxSVcgICAgICAgICAgICAgICAgICAgbm93Ogo1ayAgMC4yNnMtMzgxTUIgICAgICAgICAgICAgICAgNTBrICAgMC4wOHMtMzgwTUIKMTBrIDAuODRzLTM4ME1CICAgTl4xLjcwICAgICAgIDUwMGsgIDAuMTVzLTM4ME1CICAgCjIwayAzLjA5cy0zODBNQiAgIE5eMS44OCAgICAgICAxbWxuICAwLjI4cy0zODBNQiAgTl4wLjkKNDBrIDEyLjgxLTM4MCAgICAgTl4yLjA1ICAgICAgIDJtbG4gIDAuNTNzLTM4ME1CICBOXjAuOQ==

was: 4KD1IW                   now:
5k  0.26s-381MB                50k   0.08s-380MB
10k 0.84s-380MB   N^1.70       500k  0.15s-380MB   
20k 3.09s-380MB   N^1.88       1mln  0.28s-380MB  N^0.9
40k 12.81-380     N^2.05       2mln  0.53s-380MB  N^0.9