最佳拟合直线

import java.util.Scanner;
public class Main {

public static void main(String[] args) {
// TODO Auto-generated method stub
Scanner cin = new Scanner(System.in);
while (cin.hasNext()) {
int n = cin.nextInt();
int[] x=new int
;
int[] y=new int
;
for (int i = 0; i < n; i++) {
x[i]=cin.nextInt();
y[i]=cin.nextInt();
}
int fx=sum(x);
int fy=sum(y);
int fxy=sum(x,y);
int fxx=sum(x,x);
double a=(double)(n*fxy-fx*fy)/(n*fxx-fx*fx);
double b=(double)(fy*fxx-fx*fxy)/(n*fxx-fx*fx);
System.out.println(String.format("%.3f",a));
System.out.println(String.format("%.3f",b));
}

cin.close();
}
public static int sum(int[]...  arr)
{
int len=arr.length ;
int deeplen=arr[0].length;
@SuppressWarnings("unused")
int sum=0;
for(int i=0;i<deeplen;i++){
if(len==1){
sum+=arr[0][i];
}
else if(len==2)
{
sum+=arr[0][i]*arr[1][i];
}
}
return sum;
}

}