1 import java.util.Scanner; 2  3 public class Main { 4     public static void main(String[] args)  5     { 6         Scanner input = new Scanner(System.in); 7         long start = System.currentTimeMillis(); 8         System.out.println(su(2000000)); 9         long end = System.currentTimeMillis();10         System.out.println(end-start);11     }12     /*13    *  判断是否为素数14    * /15     static boolean sum(int n)16     {17         boolean isPrime=true;18         int s=(int)Math.sqrt(n);19         for(int i=s;i>1;i--)20         {21             if(n%i==0)22             {23                 isPrime=false;24             }25         }26         return isPrime;27     }28     /*29    *  循环遍历素数30    *  求和31    */32     static long su(int n)33     {34         long sum=0;35         for(int i=2;i<n;i++)36         {37             if(sum(i)== true)38             {39                 sum += i;40             }41         }42         return sum;43     }44 }