class ABC { int a,b; public ABC(int a, int b) { this.a=a; this.b=b; } public int compareTo(ABC x) { return a*b-x.a*x.b; } } public class XXK5 { public static void main(String[] args) { int [][]d={{3,8},{4,6},{5,6},{2,9},{3,7}}; ABC []ar=new ABC[5]; int i,k=0; for(i=0; i<length; i++) ar[i]=new ABC(d[i][0],d[i][1]); for(i=1; i<ar.length; i++) if(ar[i].compareTo(ar[k])>0) k=i; System.out.println("k="+k); } } 程序运行的结果是k= ( )。