就第二题过了。。。 public static void main(String[] args) {         // TODO Auto-generated method stub         Scanner in = new Scanner(System.in);         int n = in.nextInt();         int w = in.nextInt();         int len = n * 2;         double[] a = new double[len];         for (int i = 0; i < len; i++) {             a[i] = in.nextDouble();         }         Arrays.sort(a);         double x = a[n];         double y = a[0];         double result = 0;         if(x>=y*2) {             result = 3*n*y;         }else {             result = (x/2.0*n)+x*n;         }         result = Math.min(result, w);         System.out.printf("%.6f\n",result);     }